Schweitzer Engineering Laboratories SEL-352-1 - Phase Overpower Element Test

Date Code 20010731 Testing and Troubleshooting 11-15
SEL-352-1, -2 Instruction Manual
PHASE CURRENT UNBALANCE ELEMENT TEST
Purpose: Verify the pickup threshold of the phase current unbalance elements (Reference:
Figure 3.23).
Method: 1. Using the TARGET F command with the element name, set the bottom row of
the front-panel target LEDs to display the appropriate current unbalance element.
Select one of the current unbalance elements from the Relay Word as indicated
below:
Setting
Elements
46UB 46P, 46A, 46B, 46C
2. Apply balanced three-phase current. Decrease the current of the phase under test
until the 46 element for that phase asserts. Record the results.
3. Verify the results with the indicated setting. The phase element asserts when the
sum of the three-phase current magnitudes divided by the 46UB setting exceeds
the current magnitude of the phase under test. This translates to the following
equation, for a phase A test:
)1UB46(
II
I
CB
A
-
+

The 46P asserts when any of the phase elements assert.
PHASE OVERPOWER ELEMENT TEST
Purpose: Verify the pickup threshold of the phase overpower elements (Reference:
Figure 3.19).
Method: 1. This test requires applying voltage to only one set of voltage inputs. Remove the
parallel jumpers for the voltage inputs. These jumpers are shown in Figure 11.3
and Figure 11.4 as dotted lines.
2. Using the TARGET F command with the element name, set the bottom row of
the front-panel target LEDs to display the appropriate phase overpower element.
Select one of the phase overpower elements from the Relay Word as indicated
below:
Setting
Elements
37OP 37OP, 37OPA, 37OPB, 37OPC
3. Apply 10 V to the voltage input of the phase under test. Increase phase current (I)
slowly and observe element pickup and dropout. Record the results.