GE Multilin 745 Instruction Manual Download

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Protection Schemes

745

Transformer Management Relay

Commission

ing

http://www.GEindustrial.com/multilin

7–17

GE Multilin

4. Disable the energization detection scheme and repeat the timing test. The

operate time should be the normal operating time of Harmonic Restraint
Differential element.

l) Target, Output, Contact, and Display Operation

Verify the correct operation of all targets, output contacts, and display messages
during the percent differential tests above.

m) Blocking from Logic Inputs

Each element can be programmed to be blocked by a logic input, virtual input,
virtual output, output relay operation, or self-test relay operation. This procedure
verifies that the differential element is blockable by Logic Input 1.
1. Select Logic Input 1 by setting the

S4 ELEMENTS

DIFFERENTIAL

PERCENT DIF-

FERENTIAL

PERCENT DIFFERENTIAL BLOCK

setpoint to “Logc Inpt 1”.

2. Apply current to operate the differential element then assert Logic Input 1.

Verify that the element has reset and that all targets can be reset.

3. With Logic Input 1 asserted, remove the current and reapply. Verify that the

element did not operate.

Instantaneous

Differential Protection

Settings for this element are under the

S4 ELEMENTS

INST DIFFERENTIAL

setpoints

group. All other protective elements must be disabled to ensure that trip relay(s)
and auxiliary relays are operated by element under test. Monitor the appropriate
contact per intended settings of the FlexLogic™.

a) Minimum Pickup

1. The operating level of the Phase A element is measured by applying an AC cur-

rent to terminals H1 and G1. Monitor the appropriate trip and auxiliary con-
tact(s) as the current is increased from 0 A. Due to the auto-configuration
feature, it may be easier to read the actual differential current on the relay
rather computing it. Compare the value of the differential current at which oper-
ation is detected against the

S4 ELEMENTS

INST DIFFERENTIAL

INST DIFFEREN-

TIAL PICKUP

setpoint:

2. Check that the Trip and Message LEDs are flashing and the following trip

message is displayed:

LATCHED a (bc) Inst Differential

The message may show OPERATED instead of LATCHED if the TARGET
setpoint is “Self-Reset”.

b) Operating Time

1. To measure the basic operating time of the instantaneous differential elements,

connect an AC current signal to terminals H1 and G1 through a double-pole,
single-throw switch. The second pole of the switch starts a timer circuit that will
be stopped by the operation of the relay trip contact. Refer to FIGURE 7–5:
Timer Test Circuit on page 7–14.

2. Close the switch and set the current level to 2 times the pickup value measured

earlier. Re-open the switch and reset all targets on the relay. Ensure that the
timer circuit functions correctly.

3. Close the switch and record operating time of relay.

All differential currents are calculated using the same principal shown in

Transformer Type Selection

on page 7–8. The differential current derivation is

affected by phase shift compensation and zero sequence removal.

c) Target, Output Contact, and Display Operation

Verify the correct operation of all targets and output contacts and display messages
during testing.

NOTE