1. S
Simple Overcurrent
and Reclosing
Application with
SEL-RTS Relay Test
System
PSET 275 Lab 3
2014
Prepared for: Russell K Campbell, PE
Program Chair
Power Systems Engineering Technology
Cincinnati State Technical and Community college
Prepared by: Edward D Tucholski PSET, Smart Grid

2. Simple Overcurrentand ReclosingApplication with SEL-RTS
Relay Test System
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Purpose:
The purpose of PSET Lab 3 was to simulate sequences of a utility protection design; a
normal operating scheme, and an overcurrent and reclosing application on a feeder
breaker. The SEL-351S was configured to our SEL-AMS (Adaptive Multichannel Source)
according to the schematic on page 2. As referenced on schematic, we chose a
DC/trip/close. Three phases of 60 Hz current were connected to the relay and the
breaker status 52A contact was connected to IN101 wetted with a dc voltage matching
the logic voltage input rating on the relay, as instructed. For the dc control circuit, the
OUT101 was connected to the trip coil and OUT102 was connected to the close coil.
The current and voltage inputs from the SEL-AMS were verified as correct for this
application before proceeding. The SEL-351S was programmed using the SEL
ACSELERATOR QuickSet 5040 Software and the Template Guide provided for installation
of the template into the computer. This allowed a programming interface with the
relay. The template was loaded into the relay, after approval of design installation.
After transfer of the information to the relay and confirmation of acceptance from the
relay, the SEL-351S relay provided overcurrent protection for our simple overcurrent
and reclosing simulation. This simulation will represent the three sequence event that
the SEL Quickset Design Template provided.

3. Simple Overcurrentand ReclosingApplication with SEL-RTS
Relay Test System
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This is the SEL QuickSet Design I/O for the Lab 3 configuration. We only chose to wire
the breaker in a DC trip/close circuit configuration. The breaker could have been wired
in an AC trip/close configuration also.

4. Simple Overcurrentand ReclosingApplication with SEL-RTS
Relay Test System
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Relay Settings:
CT Ratio: 240
PT Ratio: 180
Phase Curves
 Pickup: 400
 Fast Curve Type: A
 Fast Curve Time Dial: 1
Ground Curves
 Pickup: 200
 Fast Curve Type: 1
 Fast Curve Time Dial: 1
Reclosing Relay:
 Number of reclosures: default 3 (disabled)
Here, you could set number of reclosures to N to Omit the Reclosing function.
 Reclose Interval 1: 2
 Reclose Interval 2: 10
 Reclose Interval 3: 10
 Reclose Interval 4: 0
 Rest Time for Auto Reclose: 30
 Reset Time from Lockout: 10
Given the settings of the relay, 1.73A at terminal of the board would be a normal
reading for the 240 setting on the CT, and for 480 the terminal reading would be .83A.
According to the notes from the simulation, 12kv and/or 240A would work to simulate a
fault condition that the relay would operate for.
The post fault condition on phase C indicated no current. We should expect this. With
no reclosing function enabled, the current reading on all three phases should be zero. If
one phase breaker trips and you have no reclose, you have no current in any of the
phases according to American protection practices. If we have a fault in one phase,
then we trip all phases to limit damage to loads and equipment. In our test, the LED for
phase C illuminated after the test to indicate a fault on that phase and when
investigated further, indicated no current.

5. Simple Overcurrentand ReclosingApplication with SEL-RTS
Relay Test System
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The following charts correspond to all of the available settings using the SELs Acselerator
QuickSet 5030 software.

6. Simple Overcurrentand ReclosingApplication with SEL-RTS
Relay Test System
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7. Simple Overcurrentand ReclosingApplication with SEL-RTS
Relay Test System
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Conclusion:
In our simulation of a fault condition using the SEL-351S, the relay did not work as expected.
The team encountered a password error with the system, we could not finalize the test and
achieve the desired loop sequence. Although the phase C illumination on the Target LED #24
was illuminated according to team, I am not sure how many more were illuminated. From what
I can tell from the manual, LEDs #12 (a trip has occurred), #14 (Relay has tripped on a fast
reclosing curve), and #24 (Phase C involved in fault) should have been lit. From memory, I
witnessed the middle left light illuminated, which according to the manual, indicate a remote
blocked condition. I realize from this lab that the Schweitzer Engineering Labs SEL-351S relay is
a very valuable and elaborate tool with which to configure any type of scenario of protection
for the Utility industry and personnel. I also realize without any doubt that the multivariable
programming protection scenarios present in the book seemdaunting, but, with the proper
training the relay protection programmer could be an interesting and admirable endeavor.
Being involved in this particular segment within the Utility Industry would be more interesting
than many we have covered in the program.