Protection Schemes
745
Transformer Management Relay
Commission
ing
http://www.GEindustrial.com/multilin
7–18
GE Multilin
d) Blocking from Logic Inputs
Each element is programmable to be blocked by a logic input, virtual input, virtual
output, output relay operation, or self-test relay operation. This test verifies that the
differential element can be blocked 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.
Phase Time
Overcurrent
a) Description
This procedure verifies that the phase time overcurrent element performance
matches the in-service settings. Since these elements can have any one of a
multitude of timing curves, a table of expected operating times versus applied
current should be prepared prior to testing the elements. Refer to
on page 5–50 for information on timing curves.
If the relay elements are set for a “Linear” reset characteristic when measuring the
operating times, ensure that there is sufficient time between test current injections
for the element to reset fully; otherwise, erroneous timing measurements will be
obtained. The settings for these elements are found in the
S4 ELEMENTS
!"
PHASE
OVERCURRENT
setpoints page.
b) Winding 1 Elements
To ensure that only the Phase Time overcurrent elements operate the trip relays
(and any other output relays) selected by the logic, disable all protection features
except Phase Time Overcurrent. Use the general test setup shown below:
FIGURE 7–9: General Test Setup
Connect the current supply to terminals X = H1 and Y = G1 to test the Winding 1
Phase A element. Monitor the appropriate output relays per the FlexLogic™ settings.
c) Pickup Level
1. With the interval timer disabled, apply the current signal and increase its mag-
nitude slowly until the trip relay and all the selected auxiliary relays operate. If
the element has a very inverse time characteristic, it is easier and more accu-
rate to increase the current far above the pickup level until the trip relay oper-
ates then reduce the current to just above the operate level. Then, current can
be slowly reduced below the operate level and observed for a reset action on
the trip relay. This reset level for the current should be approximately 98% of
Summary of Contents for Multilin 745
Page 2: ......
