Start A / Start B; Local Isolator N/O; Contactor Status; Switch Common - GE MOTOR MANAGER 2 Instruction Manual

2.2 INPUTS AND OUTPUTS
When the start input terminals are energized, the corresponding contactor output relay will be ener-
gized provided all other valid start conditions are met. If any trip occurs, both contactor outputs will
be de-energized. Start A input is used for all types of contactors, that is: Full Voltage Non-reversing,
Reversing, Two Speed (low speed), Wye Delta Open Transition, Inverter, Slip Ring, Autotransformer,
Part Winding or Wye Delta Closed Transition. Start B input is used for Reversing and Two Speed
2
(high speed) contactor control. Start inputs are usually momentary unless Two Wire control is
selected. Start A and B commands may also be initiated via the serial link.
The local isolator NO auxiliary contacts are used to prevent motor starts in the event of the Local Iso-
lator being in the "open" position. To prevent starts, the MM2 produces a trip when the Local Isolator
input is open. A Local Isolator Trip is automatically reset when the Local Isolator is re-closed. The
Local Isolator input can be enabled or disabled as required. The factory default is disabled.
The MM2 must know the state of the contactor at all times in order to detect discrepancies in contac-
tor close/open commands and also to display the state of the contactor. There are two contactor sta-
tus inputs on the MM2, one for contactor A, the other for contactor B.
Auxiliary contacts mechanically linked to the contactor itself are used to feed back to the contactor
status inputs. No status change following a "start" command indicates an open contactor control cir-
cuit and no status change following "stop" command indicates a welded contactor. Appropriate mes-
sages and alarms are displayed for these conditions and the status can be read via the serial port.
If the motor contactor is externally energized, the MM2 will seal in the output relay and display an
"EXTERNAL START" message. If the motor contactor is externally de-energized, the MM2 will drop
out the output relay and display an "EXTERNAL STOP" message.
These two terminals serve as the common for all switches. The MM2 switch inputs operate at 120
VAC which is supplied from these terminals.
It may be required to test a complete MCC with MM2s installed for dielectric strength. This is also
known as "flash" or "hi-pot" testing. The MM2 is rated for 1500 V AC for 1 minute or 1800 V AC for 1
second isolation between switch inputs, relay outputs, VT voltage input, supply voltage inputs and
ground terminal 13.
When performing dielectric tests, the connection to the surge ground terminal (14) must be removed.
A filter network is used on the AC input to filter out RF and EMI noise. The filter capacitors and tran-
sient absorbers could be damaged by the high voltages relative to surge ground on the AC input.
Under no circumstances should any inputs other than switches, relays, supply volt-
age, VT input, and CT inputs be dielectric tested.
WARNING
2-8

2.2.18 DIELECTRIC STRENGTH TESTING

MM2 Motor Manager 2
2 INSTALLATION

2.2.14 START A / START B

2.2.15 LOCAL ISOLATOR N/O

2.2.16 CONTACTOR STATUS

2.2.17 SWITCH COMMON

GE Power Management