H Aux 2 Coil (34/35) - GE MM3 Instruction Manual

2 INSTALLATION
h) AUX 2 COIL (34/35)
The AUX Relay 2 can be internally energized by the MM3 or externally energized by applying a +24 V DC sig-
nal to these terminals. Correct polarity is required (Terminal 35 = +24 V DC, Terminal 34 = 0 V DC).
i) OUTPUT RELAYS (36 - 47)
There are up to 4 output relays on the MM3. Contact switching rating for the output relays as well can be found
in Section 1.2: TECHNICAL SPECIFICATIONS on page 1–4.
• Contactor A Relay (46/47): non-reversing, forward, low speed, etc.
• Contactor B Relay (44/45): reversing, high speed, etc.
• AUX Relay 1 (40/41/42/43): field programmable
• AUX Relay 2 (36/37/38/39): field programmable or hardwired 24 V DC coil
j) SERIAL COMMUNICATION PORT (25/26/27)
A serial port provides communication capabilities to the MM3. Multiple MM3 relays can be connected together
with a 24 AWG stranded, shielded twisted-pair with a characteristic impedance of 120 Ω such as Belden 9841
or equivalent. The total length of communications wiring should not exceed 4000 feet. Care should be used
when routing the communications wiring to avoid power AC lines and other sources of electrical noise.
Correct polarity is essential for the communications port to operate. Terminal 25 ("+") of every MM3 in a serial
communication link must be connected together. Similarly, Terminal 26 ("–") of every MM3 must also be con-
nected together. The shield wire must be connected to Terminal 27 (485 SERIAL GROUND) on every unit in
the link to provide a common ground potential for all units. Each relay should be "daisy-chained" to the next
one. Avoid star or stub connected configurations if possible to avoid potential communication problems.
A terminating resistor and capacitor network is required to prevent communication errors. Only the last MM3
and the master computer driver should have the terminating network to ensure proper matching. Using termi-
nating resistors and capacitors on all the MM3s would load down the communication network while omitting
them at the ends could cause reflections resulting in communication errors.
GE Power Management
Figure 2–4: RS485 TERMINATION
MM3 Motor Manager 3
2.3 INPUTS AND OUTPUTS
2
2-5