2. تحدٌات ......
• تقلبات سوق الكهرباء تدعو الشركات إلى إعادة التقٌٌم النوعً للكهرباء.
• نمو الطلب على الطاقة غالبا ما ٌسبق التزوٌد خصوصا مع األسالٌب الجدٌدة لتولٌد الكهرباء
وانتظار الشركات نتائج األبحاث لمعرفة إلى أٌن ستؤول مشاكل عدم التنظٌم.
•الطاقة الرخٌصة المولدة من الطاقة النووٌة أو من الفحم أو المحطات المائٌة هً لٌست حلوال
سهلة للغاٌة لخصوصٌات البٌئة, أنظمة نقل الطاقة مصممة لنقل استطاعات محددة, وإن بناء
إمكانات إضافٌة ٌتطلب 01 سنوات.
• جودة القدرة فً تغٌرات سوق الكهرباء تخلق مشكالت إضافٌة للشركات ومراكز البحث.
• تسوٌة موضوع جودة القدرة ٌبدأ بتحدٌد االستطاعات المستهلكة على الشبكات الكهربائٌة.
• األجهزة الجدٌدة هً أكثر حساسٌة لمشكلة القدرة الناجمة عن زٌادة سرعة وكثافة الدارات
التكاملٌة.
• كلفة مشاكل القدرة اآلن وصلت إلى آالف الدوالرات فً الدقٌقة فً العدٌد من الشركات.
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
3. هل تعلم أن؟
أجهزة الكومبٌوتر النظامٌة عرضة إلضطرابات كهربائٌة مدمرة أكثر من 521 مرة كل شهر!
إنقطاع التغذٌة لمدة ساعة ٌكلف مالكً شبكات الكومبٌوتر المتوسطة النظامٌة 000,81£!
إنقطاع التغذٌة لمدة ساعة ٌكلف قطاع النقل والمواصالت 000,09£!
ٌكلف مراكز البورصة الكبٌرة !£6.5 million
000,05£! ٌكلف استرجاع one megabyteمن المعطٌات
أن ثلث المعطٌات تفقد بسبب مشاكل القدرة!
نصف أعطال الحواسب بسبب مشاكل التغذٌة الكهربائٌة!
رداءة التغذٌة الكهربائٌة ٌكلف قطاع األعمال فً أمرٌكا أكثر من $26 billionكل سنة!
نقال عن Silicon Valley Powerأن كلفة انقطاع التغذٌة عن Sun Microsystemsأكثر من $1 millionكل دقٌقة.
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
4. أنواع إضطرابات القدرة الكهربائٌة
إنقطاع كامل للتوتر
حالة عابرة
إنقطاع لحظً
جهوط إبرٌة, مسمارٌة, نبضٌة
إزدٌاد مؤقت
إرتفاع جهد
تغٌرات فً التردد
هبوط مؤقت
توافقٌات
إنخفاض جهد ضجٌج تردد عالً
Power Factor معامل القدرة المنخفض
عدم توازن األطوار الثالثة Unbalance On three-phase systems
, three-phase motors with 5% voltage unbalance exhibit 25% decrease
7. Elements of a Power Quality Problem
عناصر ردائة القدرة
التولٌد النقل التوزٌع المستهلك
المرسل قناة الربط المستقبل
( المنبع) (الشبكة) (الحمل)
إي تغٌر فً تردد أو قٌمة أو شكل موجة الجهد ٌسمى اضطرابا فً خط الشبكة ,line disturbance powerوهذا ٌسب
مشاكل فً تشغٌل األجهزة الكهربائٌة.
أسباب حدوث اإلضراب فً الشبكة ٌنسب إلى ثالثة عناصر
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
8. مىببع الخغزيت : Source
جهذ ثببج: / حردد ثببج )DC, 1-Phase/ 3-Phase AC ( 50 / 60 hz
مىببغ صغٍرة : رٌبح / خالٌب ضىئٍت /مذخراث / خالٌب انىقىد
مىبع مخىسطت : دٌسل /حىربٍه غبزي
مىببغ كبٍرة : مبئٍت / حرارٌت / وىوٌت
األحمبل: Load
أمثهت ػهى األحمبل ومخطهببث حشغٍههب:
مشبرٌغ كهراكٍمبوٌبث: Low DC Voltage, High Current
أفران ححرٌضٍت: 1-phase , High Frequency, AC 50hz
أدواث حشغٍم: Variable DC Voltage
مشبرٌغ حسخخذو محركبث: Variable Voltage Variable Frequency ( VVVF) AC
أحمبل حىاسٍب: )Un-interrupted Power Supply ( UPS
أوظمت حسود انطبئراث : )Variable Speed Constant Frequency ( VSCF
أوظمت انخىحر انؼبنً انمسخمر : / AC/ DC & DC
9. أسباب ردائة القدرة الكهربائٌة
األحمال اللخطٌة •
منابع التوافقٌات •
منابع اإلرتعاش •
منابع sage •
المبدالت المختلفة •
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
10. طرق الترابط coupling methods
الترابط المنقول الترابط المشع
الترابط من خالل ممانعة مشتركة: ٌحدث عندما ٌمر تٌار دارتٌن من خالل ممانعة مشتركة واحدة , مثال ممانعة األرضً.
وباتالً فإن الجهدالهابط على الممانعة ٌؤثر على كال الدارتٌن.
الحقول الكهرامغناطٌسٌة المشعة تحدث بسبب آالت لحام القوس الكهربائً والصواعق أو أحمال متقطعة أو محطات إرسال
إذاعً أو محطات رادار
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
11. تداخل RFI EMI
التداخل الكهرامغناطٌسً )Electromagnetic Interference (EMI
تداخل التردد الرادٌوي Interference (RFI) Radio Frequency
- التداخل الكهرمغناطٌسً أو الرادٌوي عادة ماٌكون بتردد ٌزٌد عن 100khzوٌنتقل كما األمواج
الرادٌوٌة . وبالتالً فإن خطوط القدرة وكبالتها الغٌر محجبة تسلك سلوك هوائً إستقبال ومنه تعمل
على إدخال هذه األمواج إلى األنظمة الكهربائٌة.
- ٌ EMI/RFIمكن أن ٌحدث عن طرٌق الترابط السعوي أو الترابط التحرٌضً
- بعض أنماط إضطرابات الجهد مثل الضجٌج والحاالت العابرة تحدث إما كإضطراب نمط
عادي normal modeأوكإضطراب نمط مشترك .common mode
- إضطراب النمط العادي أو المتعارض A normal or transverse modeهو
عبارة عن فرق فً الجهد غٌر مرغوب به ٌخلق بٌن خطٌن دارة ٌحمالن تٌارا , مثال فً
دارة تغذٌة إحادٌة الطور المعنٌان هما الحٌادي وخط الفاز.
- إضطراب النمط المشترك A common mode disturbanceهو فرق جهد غٌر
مرغوب به بٌن جمٌع الخطوط الحاملة للتٌار وخط األرضً. وهً تتضمن نبضات وضجٌج
EMIRFIبالنسبة لألرضً.
18. SEMI F47 voltage immunity standard
SEMI, the industry association for the semiconductor industry, has developed two voltage sag immunity
standards.
•SEMI F47 sets out the required voltage sag tolerance for semiconductor fab equipment.
•SEMI F42 explains how to test compliance with SEMI F47. (PSL helped write SEMI F42.)
You can purchase copies of these standards from SEMI for $50 each, or you can quickly and easily obtain a free
set of Application Notes on a CD-ROM from PSL -- just send us an e-mail at FreeCD@PowerStandards.com with
your name and address. (Trouble with this link? Just give us a call at +1-510-658-9600 and we'll take care of it.)
In essence, SEMI F47 requires that semiconductor processing equipment tolerate voltage sags on their ac power
line. Specifically, they must tolerate sags to 50% for up to 200 ms, sags to 70% for up to 0.5 seconds, and sags to
80% for up to one second. In addition to these requirements, SEMI F47 recommends that equipment tolerate sags
to 0% for one cycle, sags to 80% for 10 seconds, and continuous sags to 90%, but these are not part of the
requirements.
SEMI F47 suggests that semiconductor manufacturers may use this sag standard when procuring equipment.
Major semiconductor manufacturers are beginning to take this approach, including Intel, Texas Instruments,
Motorola, IBM, and others.
SEMI F42 explains how to test compliance with F47. It describes safety procedures, processing modes, test
sequences, phase connections, and reporting requirements.
SEMI F42 also distinguishes between testing equipment for "characterization" (determining the depth and duration
of sags that equipment can tolerate) and "compliance" (a pass/fail test determining if equipment complies with the
requirements and recommendations of SEMI F47).
PSL's sag generators are designed specifically to test according to SEMI F47 and SEMI F42
19. Voltage sags(dips) and swells
A typical voltage sag
فترة الهبوط تستمر من 01 مٌلً ثانٌة إلى عدة ثوان
20. Sag
Voltage sags -- or dips which are the same thing -- are brief reductions in voltage, typically lasting from a
cycle to a second or so, or tens of milliseconds to hundreds of milliseconds. Voltage swells are brief
increases in voltage over the same time range.
(Longer periods of low or high voltage are referred to as "undervoltage" or "overvoltage".)
Voltage sags are caused by abrupt increases in loads such as short circuits or faults, motors starting, or
electric heaters turning on, or they are caused by abrupt increases in source impedance, typically caused by
a loose connection.
Voltage swells are almost always caused by an abrupt reduction in load on a circuit with a poor or damaged
voltage regulator, although they can also be caused by a damaged or loose neutral connection.
A typical voltage sag.
Voltage sags are the most common power disturbance. At a typical industrial site, it is not unusual to see
several sags per year at the service entrance, and far more at equipment terminals.
Voltage sags can arrive from the utility; however, in most cases, the majority of sags are generated inside a
building. For example, in residential wiring, the most common cause of voltage sags is the starting current
drawn by refrigerator and air conditioning motors.
Sags do not generally disturb incandescent or fluorescent lighting, motors, or heaters. However, some
electronic equipment lacks sufficient internal energy storage and, therefore, cannot ride through sags in the
supply voltage. Equipment may be able to ride through very brief, deep sags, or it may be able to ride through
longer but shallower sags.
21. Sources of Sags أسباب غور التوتر
إقالع أحمال كبٌرة •
– محركات كبٌرة جدا
هبوط الشبكة •
– أحمال كبٌرة .
– حدوث أعطال.
أزمنة إزالة العطل على المغذٌات فً محطات التوزٌع: 5 to15 cycles •
مجال ضعف التوتر 20 to 50% Sag •
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
22. voltage sags أسباب
Voltage sags are brief reductions in the voltage on ac power systems. (The American "sag"
and the British "dip" have exactly the same meaning, and may be used interchangeably.)
How brief? Between 1/2 cycle and a few seconds. Disturbances that last less than 1/2 cycle
are commonly called "low frequency transients"; voltage reductions that last longer than a
few seconds are commonly called "undervoltage." Power systems have non-zero
impedances, so every increase in current causes a corresponding reduction in voltage.
Usually, these reductions are small enough that the voltage remains within normal
tolerances. But when there is a large increase in current, or when the system impedance is
high, the voltage can drop significantly. So conceptually, there are two sources of voltage
sags:
•Large increases in current
•Increases in system impedance
As a practical matter, most voltage sags are caused by increases in current. It is convenient
to think of the power system as a tree, with your sensitive load connected to one of the
twigs. Any voltage sag on the trunk of the tree, or on a branch leading out to your twig, will
cause a voltage sag at your load. But a short circuit out on a distant branch can cause the
trunk voltage to diminish, so even faults in a distant part of the tree can cause a sag at your
load.
23. It is important to understand the source of the voltage sags before trying to
eliminate them, because the wrong solution can actually make the problem worse.
For example, if you install a ferro-resonant transformer as a voltage regulator, or a
battery-operated UPS (a reasonable and common approach), but inadvertently
install it upstream from the motor that is causing your voltage sags, the voltage
sags will get worse, not better.
In most cases, the correct solution is to adjust the equipment so that it is less
sensitive to voltage sags.
Sag sensitivity - Five ways equipment fails during voltage sags
CBEMA curve - voltage sag depth and duration at world-wide semiconductor plants
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
24. إرتفاع أو إنخفاض التوتر
High or Low Voltages Sustained high and low voltages are
usually caused by the distribution system. This system of
wires and transformers that connects all electrical loads to
the utility generators has impedance. This impedance
causes the voltage to drop when current flows through the
system. The further you are from the power source and the
more current drawn, the more the voltage will drop. To
maintain the voltage as best they can, the utility will increase
the voltage so customers close to the power source will
have higher than nominal voltage while the furthest
customers will have lower than nominal voltage (maybe
much lower). Because the utility will only increase the
voltage by a certain amount, and because additional voltage
drop is caused in the user’s building wiring, voltages are
25. Most voltage sags originate within your facility. The three most common causes of facility-sourced
voltage sags are:
•Starting a large load, such as a motor or resistive heater. Electric motors typically draw 150%
to 500% of their operating current as they come up to speed. Resisitive heaters typically draw
150% of their rated current until they warm up.
•Loose or defective wiring, such as insufficiently tightened box screws on power conductors.
This effective increases your system impedance, and exaggerates the effect of current increases.
•Faults or short circuits elsewhere in your facility. Although the fault will be quickly removed by
a fuse or a circuit breaker, they will drag the voltage down until the protective device operates,
which can take anywhere from a few cycles to a few seconds.
Experts can identify the specific source of a voltage sag with an advanced power quality monitor,
such as those found at PQMonitoring.com. Voltage sags can also originate on your utility's
electric power system. The most common types of utility-sourced voltage sags are:
•Faults on distant circuits, which cause a corresponding reduction in voltage on your circuit.
Typically, these faults are removed by "reclosers", or self-resetting circuit breakers. These
reclosers typically delay 1 to 5 seconds before self-resetting. If the fault is still present when the
recloser resets, you may see a series of voltage sags, spaced 1 to 5 seconds apart. Faults on
utility systems may be phase-to-phase, or phase-to-earth; depending on the transformers
between you and the fault, you will see different levels of voltage reduction.
• Voltage regulator failures are far less common. Utilities have automated systems to adjust
voltage (typically using power factor correction capacitors, or tap switching transformers), and
these systems do occasionally fail.
26. كحالة عابرةovervaltage تجاوز الجهد
Example capacitor switching transient
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
27. The reasons for these categories were explained as follows:
•The 90% level provides an indication of performance for the most sensitive equipment.
•The 80% level corresponds to an important break point on the ITI curve and some sensitive
equipment may be susceptible to even short sags at this level.
•The 70% level corresponds to the sensitivity level of a wide group of industrial and
commercial equipment and is probably the most important performance level to specify.
•The 50% level is important, especially for the semiconductor industry, since they have
adopted a standard that specifies ride through at this level.
•Interruptions affect all customers so it is important to specify this level separately. These will
usually have longer durations than the voltage sags.
•The first range of durations is up to 0.2 seconds (12 cycles at 60 Hz). This is the range
specified by the semiconductor industry that equipment should be able to ride through sags as
long as the minimum voltage is above 50%.
•The second range is up to 0.5 seconds. This corresponds to the specification in the ITIC
standard for equipment ride through as long as the minimum voltage is above 70%. It is also
an important break point in the definition of sag durations in IEEE 1159 (instantaneous vs.
momentary).
•The third duration range is up to 3 seconds. This is an important break point in IEEE 1159
and in IEC standards (momentary to temporary).
•The final duration is up to one minute. Events longer than one minute are characterized as
long duration events and are part of the system voltage regulation performance, rather than
voltage sags.
28. voltage sag sensitivity
Why does equipment fail when there are voltage sags on ac power systems? There is one obvious way, and
four not-so-obvious ways.
1. Equipment fails because there isn't enough voltage. This is the obvious way -- if there is not enough
voltage on the ac power system to provide the energy that the equipment needs, it is going to fail. Actually, the
problem is slightly more subtle. In a typical sensitive load, the ac voltage is rectified and coverted to pulsed dc.
With a bridge rectifier, the pulsing will typically be either twice the power line frequency (for single-phase loads)
or six times the power line frequency (for three-phase loads). This pulsing DC is stored in a filter capacitor,
which in turn supplies smooth DC as raw material for the rest of the power supply: regulators, etc.
If the DC supplied by the filter capacitor drops below some critical level, the regulators will not be able to deliver
their designed voltage, and the system will fail. Note that the filter capacitor always stores energy, so there is
always an ability to ride through some sags -- after all, the ac power system delivers zero voltage 100 or 120
times each second! But with a deep enough sag that lasts long enough, the filter capacitor voltage will drop
below a critical level.
2. Equipment fails because an undervoltage circuit trips. Careful system designers may include a circuit
that monitors the ac power system for adequate voltage. But "adequate voltage" may not be well defined, or
understood. For example, if the sensitive system is running at half load, it may be able to operate at only 70%
ac voltage, even though it may be specified to operate with 90% - 110% ac voltage. So the voltage sags to
70%; the equipment can operate without a problem; but the undervoltage monitor may decide to shut the
system down.
29. 3. Equipment fails because an unbalance relay trips.On three-phase systems, voltage sags are often
asymmetrical (they affect one or two phases more than the remaining phases). Three-phase motors and
transformers can be damaged by sustained voltage unbalance; it can cause the transformer or motor to
overheat. So it makes sense to put in an unbalance relay, which is a device that shuts down the system if the
voltage unbalance exceeds some threshold, typically a few percent.
But a voltage sag that causes 20-50% unbalance for a second or two is never going to cause a motor or
transformer to overheat. It just doesn't last long enough. Still, unbalance relays with inadequate delays can
cause the sensitive system to shut down, even for a brief voltage sag.
4. A quick-acting relay shuts the system down, typically in the EMO circuit. The EMO (emergency off)
circuit in an industrial load typically consists of a normally-closed switch that can disconnect power to a
latched relay coil. If the relay operates quickly enough, it may interpret a brief voltage sag as an operator
hitting the EMO switch. The whole system will shut down unnecessarily.
5. A reset circuit may incorrectly trip at the end of the voltage sag. This is the most subtle problem
caused by voltage sags. Many electronic reset circuits are designed to operate at "power up" -- when you
first turn on the equipment, these circuits will ensure that the microprocessors all start up properly, the
latches are all properly initialized, the displays are in their correct mode, etc. These circuits are difficult to
design, because they must operate correctly when power is uncertain.
One common design detects a sudden increase in voltage, which always happens when you turn the
equipment on. Unfortunately, it also happens at the end of a voltage sag. If the reset circuit misinterprets the
end of a voltage sag, the equipment will operate perfectly during the voltage sag, but will abruptly reset itself
when the voltage returns to normal.
To make this problem even more difficult, it is quite common for different parts of a system to have different
reset circuits, so it is possible for one part of the system to be reset even when the rest of the system is not.
Without a sag generator with a good data acquisition system, this problem is very difficult to detect and
solve.
30. تنظٌم التوتر
The term "voltage regulation" is used to discuss long-term variations in voltage. It does not include short term
variations, which are generally called sags, dips, or swells.
The ability of equipment to handle steady state voltage variations varies from equipment to equipment. The
steady state voltage variation limits for equipment is usually part of the equipment specifications. The
Information Technology Industry Council (ITIC) specifies equipment withstand recommendations for IT
equipment according to the ITI Curve (formerly the CBEMA curve). The 1996 ITI Curve specifies that equipment
should be able to withstand voltage variations within +/- 10% (variations that last longer than 10 seconds).
Voltage regulation standards in North America vary from state to state and utility to utility. The national standard
in the U.S.A. is ANSI C84.1. Voltage regulation requirements are defined in two categories:
•Range A is for normal conditions and the required regulation is +/- 5% on a 120 volt base at the service
entrance (for services above 600 volts, the required regulation is -2.5% to +5%).
•Range B is for short durations or unusual conditions. The allowable range for these conditions is -8.3% to
+5.8%. A specific definition of these conditions is not provided.
Voltage regulation requirements from ANSI C84.1. This is not a universal standard; it is only used in North
America.
Other countries have different standards. For example, IEC 61000-2-2 mentions that the normal operational
tolerances are +/- 10% of the declared voltage. This is the basis of requirements for voltage regulation in EN
50160 for the European Community. EN 50160 requires that voltage regulation be within +/- 10% for 95% of the
10 minute samples in a one week period, and that all 10 minute samples be within -15% to +10%, excluding
voltage dips.
31. voltage sag كٌف نحسن من المناعة ضد
1. Find and fix the problem.
2. 2. Add a power quality relay.
3. 3. Switch power supply settings.
4. Connect your single-phase power supply phase-to-phase.
5. Reduce the load on your power supply.
6. Increase the rating of your power supply.
7. Use a three-phase power supply instead of a single-phase supply.
8. Run your power supply from a DC bus.
9. Change the trip settings.
10. Slow the relay down.
11. Get rid of the voltage sag itself.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
32. اإلرتفاع /اإلنخفاضSags / Surges
Sags / Surges are short duration changes in voltage level.
Sags (low voltage) are much more common than surges
(high voltage). Starting electric motors and other
equipment, ground faults, undersized power systems, and
lightning all produce voltage sags.
Surges may be generated when large electrical loads are
shut off.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
33. Surge إندفاع هضبة التوتر
• EN61000-4-5
• Performance Criteria B
• The surge waveform simulates the transients induced onto the AC
power line by lightning events
• The wave-shape is 1.2/50 S open circuit voltage through a 2 ohm
resistor (line to line) or 12 ohm resistor (line to ground). The short
circuit current wave-form is 8/20S
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
34. surgeماذا تعنً؟
Surge هً رشقة قصٌر من الجهد ( جهود دفقٌة أو هضبة جهد) تعرض
الحمل إلى االف الفولت. وتكون أحٌانا على شكل نبضة مسمارٌة وأحٌانا على
شكل حالة عابرة
فترة قصٌرة Short Duration --- Microseconds
طاقة عالٌة High Energy
مولدة خارجٌا Externally Generated
مولدة داخلٌا Internally Generated
35. هضبة الجهد Surgesهً
نبضة زمنها أكبر من 4.8 مٌلً ثانٌة •
توصف بالموجة المربعة أو األسٌة •
عادة ما تترافق بمنبع ذو ممانعة منخفضة •
إرتفاع الهضبة فً %09 من الحاالت ٌكون أقل من ضعفً قٌمة الجهد التشغٌل االسمً. •
36. من أٌن تأتً Surges؟
النوع المولد خارجٌا:
المدمرة – Destructiveمن الجو مثل الصواعق
المعطلة – Disruptiveفصل الشبكة الكهربائٌة
النوع المولد داخلٌا:
مسٌئة – Degradativeاألحمال التحرٌضٌة وأجهزة التقطٌع
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
37. ماهً المشاكل التً تسببها surges؟
عطل مباشر في التجهيزات قد تسب تلف .IC
هضبة الجهد المسٌئة degradative surgesقد تسبب أعطال غٌر قابلة للشرح.
فشل أداء بعض األجهزة بسبب ترابط surgesمع خطوط معطٌات.
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
38. 08% من األعطال الناجمة عن رداءة القدرة هً
بسبب الجهود اإلبرٌة و surgeالمولدة داخلٌا
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
39. ماهً وسائل الحماٌة منsurge ؟
A high voltage relief valve
It insulates during normal operation
It clamps voltage by diverting excess current to
ground during a surge
It is basically a variable resistor
Acts like an open circuit with high impedance normally
During a surge it acts like a short circuit with low
impedance
40. تقنٌات الحماٌة من Surge
انمهفبث -
األوببٍب انغبزٌت -
مقىمبث انسٍهٍىٍىو -
انفبٌرسخىرMOV -
ثىبئٍبث AvalancheانسهكىوٍتSAD -
انمكثفبث -
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
43. الحاالت العابرة & الجهودالنبضٌة واإلبرٌة
Impulses, Spikes & Transients are all names used to describe very
short duration, high amplitude voltage pulses on the power lines.
These voltage pulses often reach 6,000 volts. They are caused by
lightning that strikes on or near the power lines, utility switching, static
electricity, and switching electrical devices on or off.
Impulses damage all types of electronic and electrical equipment. The
high voltage levels puncture or weaken insulation. The fast rate of
voltage change stresses the turn-to-turn insulation of windings in
motors, transformers, solenoids, etc. The damage may not cause
immediate failure. Often the equipment is weakened and may fail days
or weeks after the event. Besides equipment damage, impulses cause
machine resets, data processing errors, and other apparently random
malfunctions.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
44. Transient ماهً الحالة العابرة
• Definition: an unanticipated change in voltage
caused by a unpredictable occurrence.
• One must differentiate between a voltage
transient and a power surge.
• Transients can be categorized in 4 basic threats.
– Lightning.
– Nuclear electromagnetic pulse.
– Electrostatic Discharge.
– Inductive switching.
46. الحالة العابرة هً
نبضة زمنها أقل من 4.8 مٌلً ثانٌة •
توصف بالموجة الجٌبٌة أو األسٌة عادة ما تترافق بمنبع ذو ممانعة عالٌة. •
قٌمتها تتراوح بٌن بضع مٌلً فولت و 00081 فولت بشروط التشغٌل الطبٌعٌة. •
حىصيفهب وفك المعيبس 2-4-00016 IEC
47. كٌف نخمد الحالة العابرة
: ٌجب األخذ بعٌن اإلعتبار اإلرشادات التالٌة
– TVS Parameters
• Stand-off Voltage (Vwm) >= Operating Voltage (Vop)
• Peak Pulse Current (Ippm) >= Source Transient Current (Is)
• Clamping Voltage (Vc) =< Voltage Withstand (Vws)
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
48. لماذاTVSS؟
Increasing Awareness of power quality
Increased speed and density of integrated circuits
Microprocessor based electronics throughout facility
Conversion from analog to digital
Switch-mode power supplies
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
50. TVSمكثفات متناهٌة الصغر
• Available from 3volt to 24volt in
unidirectional and bidirectional
configurations
• GBLC series
51. ذات سعات صغٌرة جداTVS مصفوفات
• Can be utilized for unidirectional
common mode and bidirectional
common mode or differential mode
protection applications
53. إرتعاش الجهود المتناوبة
AC Voltage Flicker
• “Flicker” is the effect caused when a large load current is
switched, creating a short-duration dip in the AC voltage (e.g.
refrigerator, when compressor switches on the lights dim
momentarily)
• Can only be measured with a custom-built test equipment -
but could be evaluated using a light bulb connected to the
same AC outlet ?
54. اإلرتعاش Flicker
اإلرتعاش مشكلة خاصة جدا وتهم اإلنسان العادي . وهً ال تقع تحت مصطلح تغٌرات الجهد.
اإلنسان حساس جدا إلرتعاش اإلضاءة الناجم عن تموج الجهد.
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
55. Brownouts إنخفاض الجهد
Brownouts are intentional under-voltages instituted by the
utility. When power demand exceeds the capacity of the
utility generators, the utility lowers the voltage to all or
some customers. This reduces the load on the generators
so they won’t burn out, but causes even more acute
equipment malfunctions and damage.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
56. عدم توازن األطوار
Three Phase Voltage Unbalance simply means the voltages on a three-phase system are
not equal.
Utilities generate three-phase AC power because it is produced and distributed at lower cost
than single phase AC or DC power, and because three phases are needed to produce
steady torque in AC generators and motors. To power single phase loads, any two of the
three power wires are connected. Voltage unbalance is usually caused by connecting more
single phase loads to one of the three phases. This situation produces unbalanced load
currents, uneven voltage drops, and thus, unbalanced voltages.
For three-phase loads, a voltage unbalance of one or two percent is usually not a problem.
However, larger voltage unbalances can cause many problems. For example, three-phase
motors with 5% voltage unbalance exhibit 25% decrease in torque, 50% increase in losses,
40% increase in temperature, and a whopping 80% decrease in life. In transmitter
applications, voltage unbalance causes severe ripple in high voltage power supplies,
straining the power supply filtering and increasing AM noise.
57. معامل القدرة
( PF ) Power factor • معامل القدرة
PF = kW / kVA –
– معامل القدرة للمحرك متأخر
– 100HP motor, 460V, 93% eff, 119A : - مثال
• (100HP x 0.746kW/HP) / 0.93 = 80.2kW
• 119A x 460V x 1.73 / 1000 = 94.8kVA
• PF = 80.2kW / 94.8kVA = 84.6% @ FL
• But … at actual load, more like 70% or less
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
58. ElectroMagnetic Compatibility المالئمة الكهرامغناطٌسٌة
• All electronic equipment is capable of radiating and absorbing
radio frequency (RF) energy.
• The principle behind ElectroMagnetic Compatibility is that
equipment should limit radiation to below a specified level, and
be able to withstand a certain level of incident RF radiation.
• The levels are given in the EMC regulations.
– BS EN 55022 (Computers)
– BS EN 55020 (Radio & TV)
• These are only a guide as circumstances vary for each location.
59. EMC 1-إعتبارات
• Good RF house keeping is vital . . .
• Spurious outputs from transmitters
– Along with unintended leakage wanted RF.
• Too much power radiated.
– Leading to excessive field strength.
• Only use as much power necessary to make the contact.
– This will reduce the EMC potential
• Your set-up
– Mode used, Antenna location, Antenna type used (Next session).
60. EMC 2-إعتبارات
• Considerations . . .
• Filters used (EMC session-2)
– Ferrite ring, High Pass, Low Pass, Band Pass Notch.
• Poor immunity of affected device
– Age, construction and use of equipment..
• Proximity for affected item.
– Coupling / Connections, Location.
• Good Quality Coax
– Quality connectors, soldered correctly and water tight.
61. RF Earths تأرٌض التردد الرادٌوي
“Mains Earth” • التستخدم أرضً القدرة
– Provide a separate earth point consisting of several copper
rods in the ground and a thick copper wire to the equipment
– Earth outer of coax cable as it enters any building.
– Do not use water / gas pipes as they may not be truly earthed.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
62. EMC وRFI وEMI ما هو
Electromagnetic Interference (EMI) ً• التداخل الكهرامغناطٌس
– Any electromagnetic disturbance that interrupts,
obstructs, or otherwise degrades or limits the
effective performance of electronics/electrical
equipment
Radio Frequency Interference (RFI) • التداخل الرادٌوي
– In general, extraneous energy, from natural or
man-made sources, that impedes the reception of
desired signals.
Electromagnetic Compatibility (EMC) • المالئمة الكهرامغناطٌسٌة
– A device is compatible with its electromagnetic
(EM) environment and it does not emit levels of EM
energy that cause electromagnetic interference
(EMI) in other devices in the vicinity.
63. EMI مسببات
المنابع •
Signal / Power energy in EM fields – حقول كهرامغناطٌسً لخطوط القدرة
Reflections from un-terminated transmission lines – إنعكاس من تهاٌات خطوط إرسال
Electrostatic Discharges (ESD) ً– تفرٌغ كهراستاتٌك
• التربط
Inductive / Capacitive coupling ًترابط سعوي أو تحرٌض –
Common impedance coupling ترابط بممانعة مشتركة –
Radiated electromagnetic fields حقل كهرامغناطٌسً مشع –
المستقبالت •
Unnecessarily high bandwidth – عرض مجال واسع غٌر مرغوب
Low noise margins – هامش ضجٌج منخفض
64. تقنٌات تخفٌض EMI
• تخمٌد منابع اإلشعاع
موافقة خطوط اإلرسال –
تخمٌد عناصر اإلشارة الرادٌوٌة الغٌر ضروري –
تخفٌض مستوٌات الجهد والتٌار –
مرشح مسالم على خطوط التغذٌة وعلى خطوط اإلشارة وعلى نبضات النزامن –
• تخفٌض الترابط
– توضع للعناصر وتوزٌع مسار الخطوط.
– التحجٌب.
– تأرٌض .
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
65. كٌف تعمل المرشحات على تخفٌض EMI
1V
-1/1V Int Z 1R
05 001
ٌخمد مرشح التمرٌر المنخفض
1mHz
1C
توافقٌات اإلشارة التً هً أعلى من
TVS
2C
القطع ) (fcمن أجل اإلختبار نختار
TVS
20pf 20pf 50 Load
1 Dو2 Dمن نوع دٌود TVذو
سعة وصلة ,20pFسوف TVS
تحمً من الحالة العابرة وتخمد
اإلشارات الغٌر مرغوبة التً فوق تردد
القطع
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
68. ESD المناعة ضد تفرٌغ الشحنة الساكنة
• EN61000-4-2
• Performance Criteria B
• ESD events create high-speed transients that can:
• Permanently damage ICs
• Cause false resets or other spurious reactions
• The performance criteria is B - so some degradation in
performance is permitted during the test but the device MUST
recover without user intervention.
• ESD events caused by people discharging directly to the
product or to nearby objects
69. توضع عناصر دارة صحٌح
حافظ على جعل مسارات نبضات التزامن أقصر ما ٌمكن.
حاول إبعاد مسارات نبضات التزامن بعٌدة ما ٌكمن عن حواف البطاقة اإللكترونٌة .PCB
دعم الدارة بمكثفات إزالة الترابط الرادٌوي وخصوصا على الدارات المتكاملة التً تعمل على
التقطٌع وحاول وصلها أقرب ماٌمكن من أرجل .
إن مكثفات إزالة الترابط فعالة فقط فً الترددات حتى ,100MHzفً الترددات األعلى من ذلك ٌتم
تحقٌق إزالة الترابط بجعل وحدات التغذٌة أقرب ما ٌكون ومن خالل صفائح معدنٌة مؤرضة.
الخطوط الحاملة لنبضات التزامن ٌجب وصل نهاٌاتها بمقومات عندما طولها ثالثة أضعاف زمن
صعودها لحماٌتها من الطنٌن على خطوطهاألن ممانعة المسار ال تساوي المصدر مقسومة على
الحمل.
.tr = rise time in nS
70. توضع عناصر دارة صحٌح
Provide filtering on all interface ports (including AC & DC power )
RF caps to a “clean” ground (typically chassis), common mode chokes or ferrite
beads make ideal circuit elements
Include the filter components on ALL signal lines, including ground (especially
where the ground is a digital signal ground)
71. I/O Interfaces التداخل بٌن الخرج والدخل
If possible, use PCB connectors with metal back shells as these can
prevent high frequency signals radiated from the board from coupling
onto the signal lines after the filter
Shields ideally terminate 360 to the enclosure (NOT to digital ground).
Shielded cables should have the shield terminated to the enclosure at the
“noisy” end(s) - single ended grounding at rf does not work
Never use pigtails to terminate shields - at best they make a shielded
cable ineffective, at worst they can increase emissions.
XLR cables are not designed for effective use of the shields - if you
cannot terminate the shield directly to chassis (because of low frequency
ground loops) tie to chassis using ceramic capacitors (alternatively create
a capacitor on the PCB)
72. الحلول الوقائٌة
• الحصانة من اإلشعاعRadiated Immunity
– Solve problems in a similar manner to radiated emissions
– Restrict bandwidths
– Add common mode filtering to audio inputs
– Pay particular attention to high-gain stages - make sure they are
provided with adequate rf decoupling
• الحالة العابرة السرٌعةFast Transients
– Transzorbs on I/O lines, filtering, enclosure design all have an
effect
• إنبعاث الجهدSurge
– Power supply design could incorporate MoVs line-to-line (line-to-
ground typically prohibited by Safety standard)
– AC line filters can reduce surge effects.
75. التشوه التوافقً
التشوه التوافقً هو تشوه فً شكل الموجةالجٌبٌة . ٌحدث بسبب مرور تٌارات أحمال
غٌر جٌبٌة فً ممانعة مشتركة فً نظام التوزٌع الذي بدوره ٌؤدي إلى خلق جهد غٌر
جٌبً على خطوط التوزٌع.
إن وحدات التغذٌة وأنظمة قٌادة المحركات التً تعتمد أنصاف النواقل وتٌارات مغنطة
المحوالت جمٌعها تسبب تشوهات توفقٌة.
تشوهات الجهد هذه قد تؤذي أو تخل فً أداء العدٌد من األجهزة المصولة على خطوط
الشبكة المشوهة.
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
76. اآلثار الضارة للتشوه التوافقً
• ضجٌج سمعً وإهتزاز مٌكانٌكً فً التجهٌزات الكهرومغناطٌسٌة كالمحوالت والمحركات و لوحات
الحماٌة (القواطع).
• إرتفاع الحرارة فً المحوالت والمولدات والكبالت ومكثفات التعوٌض.
• سوء أداء بعض تجهٌزات التحكم اإللكترونٌة الحساسة.
• فتح قواطع الحماٌة بشكل غٌر مبرر.
• إرتجاف اإلضاءة وشاشات التلفزة والحواسٌب.
• تشوه الصوت فً األنظمة الصوتٌة.
• إنخفاض عامل اإلستطاعة الغٌر مفسر.
• تحمٌل الزائد للناقل الحٌادي خصوصا عند وجود التوافقٌة الثالثة.
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
77. مصادر التوافقٌات & اإلرتعاش
• العناصر الفٌرومغناطٌسٌة
– المحوالت(اإلشباع , الالخطٌة).
• عناصر القوس الكهربائً
– مصابٌح الفلورٌسانت.
– أجهزة اللحام بالقوس الكهربائً.
– أفران القوس الكهربائً.
• العناصر اإللكترونٌة المفتاحٌة
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
78. Conquering Harmonic Resonance can be accomplished by:
(1) adding or subtracting capacitance from the system to move the
parallel resonance frequency to one that is not deleterious;
(2) adding tuned harmonic suppression reactors in series with the
capacitor to prevent resonance; (3) altering the size of non-linear
devices. It is important that the tuned frequency, for the 5th harmonic,
be at approximately the 4.7th harmonic to account for tolerance in
manufacturing and to remove the largest offending portion of the 5th
harmonic. Parallel resonance will occur around the 4th harmonic, at a
much lower amplitude and in an area that does no harm to the
system or capacitor. Tuning lower than 282 Hz is not efficient in
removing large portions of the offending harmonic
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
80. where: h = harmonic order
KVAsc : available short circuit at point of capacitor bank installation
KVAR =capacitor bank size
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
84. طيف مىجت الخيبس لمخفج اإلضبءة
• High frequency components which lead to EMI are reduced by the choke.
85. المقومات وحٌدة الطور
مثال: وحدات تغذٌة الحواسب, شواحن البطارٌات
Typical computer power supply front-end
• The rectifier conducts only when the line voltage magnitude exceeds the
capacitor voltage.
• The capacitor gets charged by drawing current at the peak of the voltage
cycle and gets discharges slowly into the switching regulator between the
voltage peaks.
• Thus the circuit draws short pulses of current during line voltage peaks.
87. تٌار الحٌادي فً جسر تقوٌم ثالثً الطور
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
88. Sequence Classification of Harmonics
• In AC systems, the current
and voltage waveforms have
rotational symmetry.
– even harmonics will not be
present.
• Power system harmonics are
hence predominantly the
odd, i.e 3rd, 5th, 7th, etc.
89. مقوم ثالثً الطور
Six-pulse Rectifier
• Used in motor drives, traction, electrochemical plants, etc.
• The high inductance in the dc side causes the dc current, Id to
be essentially constant.
90. مقوم ثالثً الطورSix-pulse Rectifier
• The Fourier series for the line current for a diode rectifier is:
2 3 1 1 1 1
ia ( t)
Id
sin t sin5 t sin 7 t sin 11 t sin 13 t ...
5 7 11 13
• For symmetrical ideal triggering, only harmonics of the order
6n±1 are present in the AC side currents.
• The presence of source reactance and commutation effects lead
to smoother current waveforms.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
91. Supply voltage and current waveforms for three-phase bridge
with highly inductive load
92. Twelve-pulse Rectifier (cont.)
• Used in high power motor drives, traction, hvdc converters, etc.
• The Fourier series for the line current for a twelve-pulse diode rectifier is:
2 3 1 1
ia (t ) I d sin t sin 11t sin 13t ...
•
For symmetrical ideal triggering, only harmonics of the 13 12n±1 are
11 order
present in the AC side currents.
Supply voltage and current waveforms for twelve pulse bridge with highly inductive load
94. Integral-cycle Controllers or Pulse Burst Modulation (PBM)
• This technique is used in applications such as heating, ovens,
furnaces, etc.
• Subharmonics are predominant. DC component can also be
present.
• High frequency harmonics above 200 Hz are practically absent.
Pulse-burst-modulation power conditioning .
Current wave: n=6; g=4/6
Harmonic spectrum for g6/8.
Currents generated by a typical PBM system.
96. الخىافميبث والمحىالث
إرتفاع حراري للمحول وعطب العزل وذلك ألسباب عدة:
زٌادة تأثٌر الظاهرة القشرٌة skinوظاهرة التجاورproximity
دوران التوافقٌات فً الملف اإلبتدائً . circulating
تزٌد من ضٌاعات اإلبطاء hysteresis
تزٌد من ضٌاعات التٌارات اإلعصارٌة eddy
تٌار مستمر فً الملف اإلبتدائً DC
AFC AFC
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
97. الخىافميبث والمحىالث
Many transformers are rated by
“K factor” which simply describes
their ability to withstand harmonics.
Transformers may also be derated
to compensate for the additional
heating caused by harmonics.
Improved transformer designs have
also been developed, with oversized
AFC AFC
neutral busses, special cores, and
specially designed coils.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
98. تأثٌر التوافقٌات على المحوالت
ضٌاعات المحول الناتجة عن التوافقٌة الثالثة TRIP
•تقسم ضٌاعات المحول إلى ضٌاع الملفات وضٌاع النواة الحدٌدٌة
• ضٌاع النواة تلقى إهتمام أقل ألنها ناتجة من السٌالة المولدة فً النواة من قبل الجهد المستمر
• ضٌاع الملفات ٌزداد مع إزدٌااد I2Rوالضٌاعات الشاردة
تأثٌر التوافقٌة الثالثة:
• إجهادات مفرطة ناجمة عن الحرارة
•إنهٌار العازلٌة
•مردود تشغٌلً منخفض
•زمن حٌاة قصٌر
•ضجٌج صوتً
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
99. الخىافميبث ومكثفبث حصحيح المذسة
مكثفات تصحٌح عامل القدرة قد تسبب طنٌن تسلسلً أو طنٌن
تفرعً فً نظم القدرة.
إذا تولدت توافقٌات تقع ضمن تردد طنٌن النظام , فً هذه الحالة
سوف تضخم التوافقٌات
100. الخىافميبث ومكثفبث حصحيح المذسة
:مثال
Assume a 1500 kVA supply xfmr,
1500 kVA with a 5.75% impedance.
5.75%
600 kVAC Also assume 600 kVA of power
correction capacitors on the system
:ٌعرف تردد الطنٌنً التوافقً بالعالقة
kVAsc 1500 / 0.0575 = 6.6
hr = =
kVAC 600
101. الحلول القدٌمة فً معالجة التوافقٌات Leo Craig
1-وضع عامل أمان كبٌر عند حساب منابع الطاقة والكبالت والقواطع وهوحل مكلف جدا
وبطبٌعة الحال ال ٌنفً وجود التوافقٌات على الشبكة.
2- وضع محوالت بتوصٌالت مختلفة للحد من حركة التوافقٌات الثالثة ومضاعفاتها (
التوافقٌة التاسعة ) وهو للحد من آثار التوافقٌة الثالثة لحماٌة كابل الحٌادي. وٌبقى حال
جزئٌا مكلفا.
وهً خاصة لتخمٌد التوافقٌة ) -36 pulse Bridgeاستخدام جسور خاصة تدعى (
d,yالخامسة والسابعة . وطبعا لكونها محوالت صرفة (ذات لف مختلف لمفات الثانوي
)متوضعة تسلسلٌا بٌن المنبع والحمل فٌها فهً مكلفة للغاٌة وتعتبر حال جزئٌا.
4- دارات الطنٌن المولفة ( الفالتر الطنٌنٌة ) والتً تتألف من ملف ومكثف موصولٌن بشكل
دارة طنٌن تعٌٌر على التردد المرغوب التخلص منه بحٌث تمرر هذا التردد دون غٌره إلى
الخط الحٌادي أو األرضً . وكسابقتها هً حل مكلف وجزئً.
5- ملف تسلسلً بٌن المنبع والحمل تكون ممانعته عالٌة بالنسبة للترددات األكبر من التردد
) بحٌث تخفض مجموع التوافقٌات الكلً . وهً تعتبر حال جٌدا للتوافقٌات 50hzاألساسً (
الكبٌرة ولكنها اقل فعالٌة بالنسبة للتوافقٌات الصغٌرة الهامة فهً كغٌرها من الحللول تعتبر
حال جزئٌا.
102. التوصٌات العملٌة للتعامل مع مشكلة التوافقٌات
Identify the required PCC and apply techniques that are most cost effective for that location.
Add a line reactor (or DC link choke if possible) to any un-buffered 6 pulse drives.
Never use power factor correction capacitors at the input (or output) terminals of a drive.
Active filters are most cost effective on larger multi-drive systems to correct for both displacement and distortion
power factor.
For an even number of equally sized drives, consider a Pseudo 12 pulse solution by placing half of the load on a
phase shifting delta wye transformer.
Design the system to Isolate linear and non-linear loads and create two systems with 5% and 10% voltage limits
respectively.
If passive filters are used on generator power, select a passive filter with an LC dropout contactor terminal block.
Take the time to understand the benefits and drawbacks of each type of mitigation solution to assure you meet
the requirements of the application
and that you can live with any negative effects created by the chosen harmonic solution.
Consider an active front end if the application requires regenerative operation and harmonic compliance.
Perform a preliminary computer analysis and explore the effects of using various compliance methods.
103. كٌف نخفض التٌار التوافقً
• خانق ترابط مستمر داخل نظام القٌادة DC link choke within the drive
• مفاعل خط line reactor
• مرشح مسالم passive filter
• مر شح فعال active filter
• تعدد األطوار multi-pulse
• مبدل مقوم فعال active rectifier / converter
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
104. أنواع المرشحات
المرشحات المسالمة Passive filters •
تؤمن مسار ذو ممانعة منخفضة إلى األرض عند تردد الرنٌن –
تستخدم المكثفات كمرشحات فعالة. –
تستخدم عناصر RLCمولفة . –
إقتصادٌة. –
المرشحات الفعالة Active filters •
معوض ستاتٌكً لإلستطاعة الردٌة. –
تحقن تٌارات توافقٌة ( أو توترات) معاكسة بالطور للتوافقٌة الموجودة –
تستخدم عناصر مثل مفاتٌح أنصاف النواقل ومضخمات. –
غالٌة الثمن. –
105. Passive Filtersالمرشحات المسالمة
• النمط ذو الطنٌن التسلسلً ٌؤمن ممانعة منخفضة عند تردد الطنٌن
• النمط ذو طنٌن التوازي ٌؤمن ممانعة عالٌة عند تردد
106. Capacitor as a Filter المكثف كمرشح
• المكثف التفرعً هو أبسط شكل للمرشح المسالم
إقتصادي -
(Q) – أٌضا ٌؤمن تعوٌض قدرة ردٌة
• delines for sizing capacitive filters
– resonance between capacitor and circuit inductive
reactance should not occur exactly at an integer
multiple of fundamental frequency.
– sensitivity of resonant point to drift in capacitor value
should be investigated,
– voltage and var support provided should not be
excessive,
– IEEE Standard 18 should be consulted for sizing and
placement of capacitor.
117. Motor Derating vs. Harmenic Voltage Distortion
This chart requires a calculation for the Harmonic Voltage Factor or
HVF based on weighted individual harmonic component levels. Since
the motor impedance is lower for the lower harmonic components, they
will cause more heating and thus carry more weight. To determine the
motor de-rating factor, the following formula should be used.
for values of n from 0 to infinity.
135. Recommendations Practices to Aid in
Harmonic Compliance
• Identify the required PCC And apply techniques most cost effective for that location.
• Add a line reactor (or DC link choke if possible) to any un-buffered 6 pulse drives.
• Use Active Filters on multi-drive systems to correct displacement / distortion.
• For an even number of equally sized drives, consider a Pseudo 12 pulse solution by placing half of
the load on a phase shifting delta wye transformer.
• Design the system to Isolate linear and non-linear loads and create two systems with 5% and 10%
voltage limits.
-الدكتور المهندس محمد منذر القادري
munthear@gmail.com
136. Recommendations Practices to Aid in Harmonic Compliance
• For passive filters on generator power, select a filter with an LC dropout contactor terminal
block. Limit leading power factor.
• Take time to understand the benefits and drawbacks of each type of mitigation solution to
assure you meet the requirements of the application and that you can live with any negative
effects created by the chosen harmonic solution.
• Consider an active front end if the application requires regenerative operation and harmonic
compliance.
• Perform a preliminary computer analysis and explore the effects of using various compliance
methods.
• Never use power factor correction capacitors at the input (or output) of a drive.
139. - الحذود المىصى بهبIEEE 519
The Institute of Electrical and Electronics Engineers (IEEE)
has set recommended limits on both current and voltage
distortion in IEEE 519-1992.
THD (voltage) نوع التطبٌق
3% Special Hospitals and Airports
5% General Commercial Industrial
10% Dedicated Non-lineal load system
careful review of the IEEE-519-1992 document reveals three levels of
compliance with regard to voltage distortion. These levels are set at and
defined as:
140. 915 - IEEEالحذود المىصى بهب للخشىهبث
تشوه التٌار التوافقً األعظمً كنسبة من تٌار الحمل
رقم التوافقٌة الفردٌة
Isc/IL 11< 71<11<h 32<17<h 53<23<h TDD
02< 0.4 0.2 5.1 6.0 0.5
05-02 0.7 5.3 5.2 0.1 0.8
001-05 0.01 5.4 0.4 5.1 0.21
0001-001 0.21 5.5 0.5 0.2 0.51
0001> 0.51 0.7 0.6 5.2 0.02
: Iscتٌار قصر الدارة األعظمً عند نقطة الربط المشتركة (PCC Point of Common Coupling
تٌار الحمل المطلوب األعظمً عند نقطة PCC : IL
141. حخميذ الخىافميبث Attenuation of Harmonics
المفاعلة التحرٌضٌة
طرٌقة العمل : إضافة مفاعلة خط أو محول عزل لتخمٌد التوافقٌات
منخفض الكلفة الفوائد:
تقانة بسٌطة
االهتمام: ٌخدم فً تقدٌم تخفٌض فً توافقٌات المرتبة العلٌا. وله تأثٌر قلٌل على
التوافقٌات الخامسة والسابعة
بسبب ترافق ذلك مع هبوط فً الجهد. ٌوجد حدود فً إضافة هذه المفاعالت
142. حخميذ الخىافميبث Attenuation of Harmonics
المرشحات المسالمة
ٌؤمن ممر ممانعة منخفضة بالنسبة للترددات التوافقٌة الى األرض طرٌقة العمل:
ٌمكن أن تولف على تردد بٌن التوافقٌٌن الشائعٌن بحث ٌخدم فً تخمٌد الترددٌن الفوائد:
تولٌف الفالتر تحتاج إهتمام مركز من قبل الفنٌٌن االهتمام :
تختلف الفالتر بحجومها وال ٌمكن تحدٌد مقاٌٌس لها
تبدي حساسٌة عالٌة ألي تغٌٌر فً مواصفات النظام
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
143. Attenuation of Harmonics حخميذ الخىافميبث
المرشحات الفعالة
طرٌقة العمل: ٌحقن توافقٌات مساوٌة ومعاكسة إلى نظام القدرة لحذف تلك التوافقٌات المولدة من أجهزة
أخرى
الفوائد: ٌضمن تخفٌض فعال للتوافقٌات إلى مستوٌات منخفضة مطلوبة
االهتمام : ٌتطلب إنفرتر أداء عالً لحقن التوافقٌات وهذا مكلف
ترانستورات القدرة المستخدمة تتعرض إلى ظروف التً ٌخضع لها الخط.وبذلك نواجه مشكلة الوثوقٌة
الدكتور المهندس محمد منذر القادري-
munthear@gmail.com
144. Attenuation of Harmonics حخميذ الخىافميبث
مقومات 21 نبضة
:طرٌقة العمل Two separate rectifier bridges supply a single
DC bus. The two bridges are fed from phase-
shifted supplies.
:الفوائد Very effective in the elimination of 5th and 7th
harmonics.
Stops harmonics at the source.
Insensitive to future system changes.
Concerns: May not meet the IEEE standards in every
case.
Does little to attenuate the 11th and 13th
harmonics.
145. حخميذ الخىافميبث Attenuation of Harmonics
مقومات 81 نبضة
طرٌقة العمل: محول إزاحة الطور المتكامل ومقوم الدخل الذي ٌستجر فً الغالب موجة جٌبٌة نقٌة
من المنبع
ٌلبً المعٌار IEEEفً جمٌع الحاالت الفوائد:
ٌخمد جمٌع التوافقٌات حتى التوافقٌة 53
ٌوقف التوافقٌات عند المنبع
غٌر حساس لتغٌر مواصفات النظام
االهتمام: ٌمكن أن ٌكون غالً الثمن عند استطاعات منخفضة
146. ً ستاتٌكVar معوض إستطاعة ردٌة
• Consists of electronically switched capacitor and/or inductor.
• Some SVC technologies
– Thyristor Controlled Reactor (TCR) with fixed capacitor (FC)
– TCR with thyristor switched capacitor (TSC).
• The Adaptive Var Compensator (AVC), developed at the University of
Washington, is essentially a bank of TSCs.
147. FACTS and Custom Power Devices
• The other families of power electronic devices, very closely related to
the active filters, are
– Flexible AC Transmission System (FACTS) devices,
– Custom Power Devices.
• FACTS devices are intended for [4]
– greater control of power transmission,
– maximize utilization of existing transmission lines,
– reduction of generation reserve margin,
– prevention of cascading outages,
– damping of power system oscillations.
148. Static Condenser (STATCOM) ًالمكثف الستاتٌك
Figure 22: Functional
block diagram of a
STATCON.
• FACTS and Custom Power Device
– reactive power compensation,
– voltage regulation (by reactive power compensation),
– harmonic current compensation.
• Behaves as a voltage source connected in shunt to the power
system through an inductor.
