D Switch Inputs - GE MM3 Instruction Manual

C.1 DO'S AND DONT'S
d) SWITCH INPUTS
The MM3 has 16 switch inputs that operate on 120 V AC when the control voltage switch is set to 120 V AC
and 240 V AC when the control voltage switch is set 240 V AC.
It is recommended that the switch terminals are activated from the same source as is con-
nected to Terminals 23 and 24. The common of the switch inputs is though Terminal 23.
NOTE
An external source can be used to supply the circuitry into the MM3 switch inputs providing that the external
source is in phase with the control voltage of the MM3. The MM3 switches the inputs on and off internally, to
minimize power consumption, at a frequency determined by the control voltage. If the external source is not in
phase with the control voltage to the MM3, the timing will be off which could cause errors when reading the
switch inputs. If an external source is used to supply the control signals to the MM3 switch inputs, the source
C
should be fused to protect against fault conditions in the circuitry.
e) THERMISTOR AND ANALOG INPUTS
Due to the small voltage levels coming into the MM3 from the thermistor and external analog device, shielded
cable is recommended to minimize any noise that may be picked up. These wires should be routed away from
any power carrying cables.
f) STOP SWITCH INPUT
The STOP switch input on the MM3 MUST be energized before the MM3 is available to perform a start. If the
contactor is being energized and de-energized externally to the MM3, this terminal will need a jumper from ter-
minal 24 before the MM3 will seal in Contactor A.
g) CONTACTOR STATUS FEEDBACK
The MM3 MUST see feedback from Contactor A and Contactor B auxiliary contacts into the applicable status
switch inputs (Terminals 15 and 16) within 1 second of closing the contactor. If this feedback is not received,
the MM3 will open the contactor instead of sealing it in, and will alarm with an OPEN CONTROL CIRCUIT.
C-2 MM3 Motor Manager 3
APPENDIX C
GE Power Management