Functional Tests; Phase Current Functions - GE MOTOR MANAGER 2 Instruction Manual

7 TESTING

7.2 FUNCTIONAL TESTS

Any phase current protection is based on the ability of the MM2 to read phase input currents accu-
rately. Make the following settings:
S2: PROTECTION \ MOTOR PROTECTION THERMAL \ FULL LOAD CURRENT = 100A.
S1: CONFIGURATION \ STARTER \ STARTER TYPE = FV NON REVERSING.
To determine if the relay is reading the proper input current values, inject different phase currents into
the CT inputs and view the current readings in A1: DATA \ MOTOR DATA. The displayed current should
be equal to the actual injected current.
Phase current values will be displayed even if the motor status is stopped; that is, contactor A has
not been activated by a start command. Very low currents are displayed as 0 A.
Once the accuracy of the phase CT inputs has been established, various phase alarm and trip condi-
tion tests can be performed by altering setpoints and injected phase currents.
To simulate an overload condition, enter S2: PROTECTION \ MOTOR PROTECTION THERMAL and alter and
store OVERLOAD CURVE NUMBER = 4 and FULL LOAD CURRENT = 50A. PHASE CT PRIMARY AMPS should
be set to 100A. Close the start A input and note that the RUNNING LED goes on. Inject a current of
10 A into all three phases. The relay will display a current value of:
displayed current = actual injected current × 100/5 = 10 × 100 / 5 = 200 A.
This represents 4 times the phase FULL LOAD CURRENT setpoint. Therefore, based on a 400% over-
load and curve #4, Contactor A will change state 23 seconds after the overload is first applied. When
this occurs, the Running LED turns off and the Tripped and Stopped LEDs are lit. After the trip has
occurred, use the A1: DATA \ MOTOR DATA actual values to verify that the thermal capacity used is now
100%. Press the RESET key to reset the MM2.
To prepare the MM2 to simulate an unbalance alarm, make the following settings:
S2 PROTECTION \ MOTOR PROTECTION OPTIONS \ PHASE UNBALANCE ALARM = ENABLE
S4 CONTROL \ AUX RELAY 1 CONFIG \ AUX RELAY 1 FUNCTION = ALARMS
S4 CONTROL \ AUX RELAY 2 CONFIG \ AUX RELAY 2 FUNCTION = TRIPS
Inject 5.0 A into all three phase CTs. The MM2 displays a balanced phase current of 100 A for each
phase. While still viewing actual values, slowly begin decreasing phase 1 current until the UNBAL-
ANCE ALARM message comes on. AUX Relay 1 should energize when the alarm is present. Unbal-
ance is calculated as follows:
For average currents greater than motor full load:
I I
–
>
n av
15% (alarm)
---------------- -
I
av
For average currents less than the motor full load:
I I
–
>
n av
15% (alarm)
---------------- -
I
fl
where: I = RMS current in any phase with maximum deviation from the average current I
n
I = average of the 3 phase currents; I
av
I = phase A current; I
a
GE Power Management
30% trip
I
with
30% trip
a
I
= ------------------------ -
av
= motor full load current
fl
= phase B current; I
b
MM2 Motor Manager 2
7.2 FUNCTIONAL TESTS

7.2.1 PHASE CURRENT FUNCTIONS

I I
+ +
b c
3
= phase C current
c
7
av
7-3