BECKWITH ELECTRIC M-3425, Instruction Book

Page: 164 / 225

6–27
Testing – 6
46 Negative Sequence Overcurrent Inverse Time
VOLTAGE INPUTS:Configuration V1
CURRENT INPUTS: Configuration C1 (MODIFIED)
TEST SETTINGS: Pickup Inv Time P % (3 to 100)
Time Dial Setting K (1 to 95)
Maximum Trip Time D cycles (600 to 65,500)
Programmed Outputs Z OUT ( 1 to 8)
Function 27TN, 32, 50 Disable
Functions 51T, 51V, 87 Disable
Function 46 Definite Time Disable
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NOTE: Although no voltage input is required for the testing of the 46 function, it is suggested that
Nominal Volts be applied to restrain the functions which use both voltage and current inputs for
operation. If other functions operate during these tests they will need to also be disabled for the test
and enabled after the tests are complete.
1. Disable functions as shown. See Section 3.2, Initial Setup Procedure/Settings, Configure Relay
Data, for procedure.
2. Confirm settings to be tested.
3. Connect inputs in Configuration V1 and C1 (MODIFIED) designated above. The modification to C1
(See Section 6.1, Equipment/Test Setup for configuration) is to exchange Current input 2 and 3
(phase B current = input 3 and phase C current = input 2.)
4. The current pickup level at a percentage setting is: Pickup current = (P% ÷ 100) x (Nominal
Current) where the Nominal Values have been programmed in the system setup data described in
Section 2.1, Configuration and should be recorded on Figure A-2, Communication Data and Unit
Setup Record Form.
5. Test levels may be chosen at any percentages of Nominal Current which are a minimum of 5%
higher than the pickup percentage, P%. (Suggest 4 or 5 test levels chosen and calculated in
amps.)
6. Set the three-phase voltages V
A
, V
B
, and V
C
to the Nominal Voltage.
7. Time Test: With output contacts (Z) connected to stop the timer, apply currents equal to the
chosen test levels calculated in step 5 and start timing. The operating time will be as read from
Figure 2-11, Negative Sequence Inverse Time Curves, negative sequence current in % of
Nominal Current and appropriate K (Time Dial) setting, or the maximum trip time (whichever is
faster). Repeat this step for all test levels chosen.
8. Reset Time Test: If it is desired to test the reset time, begin timing immediately when the input
current is reduced below the pickup value. Holding the TARGET RESET button in, stop timing
when the TARGET LED goes out. The time should be approximately 4 minutes.
9. If testing is complete, enable any functions disabled for this test. If other tests are to be
completed, check the proper functions to disable for the next test and proceed from this point.
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NOTE: If retesting is required, the unit should be powered down or wait 4 minutes before the next
test to assure resetting of the timer.
(For proper testing, use I
≤
3 x CT rating)