Lenze MCH Series - Manual (Page 36)

32 13435744_EDBMH01_v13
14 CONTROL WIRING
14.1 GENERAL
This section describes control wiring for standard MCH drives. Refer to Appendix A for
control wiring for the Bypass option, or Appendix B for control wiring for the Option Box.
14.1.1 KEYPAD CONTROL
The drive can be controlled by the keypad or by control devices wired to the terminal
strip. The drive will run from the keypad “out of the box”, requiring no connections to the
terminal strip. Refer to Section 13.0 - KEYPAD CONTROL.
14.1.2 CONTROL WIRING VS. POWER WIRING
External control wiring MUST be run in a separate conduit away from all other input and
output power wiring. If control wiring is not kept separate from power wiring, electrical
noise may be generated on the control wiring that will cause erratic drive behavior. Use
twisted wires or shielded cable grounded at the drive chassis ONLY. Recommended
control wire is Belden 8760 (2-wire) or 8770 (3-wire) or equivalent.
Torque the control terminals to 2 lb-in (0.2 Nm). Be careful not to overtorque the
terminals, as this will cause damage to the terminal strip. This is not covered under
warranty and can only be repaired by replacing the control board.
14.1.3 TB-2: CIRCUIT COMMON
The TB-2 terminals are used as circuit common for the start/stop, input select, analog
input and analog output functions. There are three TB-2 terminals available on the
terminal strip and they are all internally connected to each other on the main control
board. If necessary TB-2 may be connected to chassis ground.
NOTE
TB-2 MUST be connected to chassis ground when using serial
communications.
14.1.4 SURGE SUPPRESSION ON RELAYS
Current and voltage surges and spikes in the coils of contactors, relays, solenoids, etc,
near or connected to the drive, can cause erratic drive operation. Therefore, a snubber
circuit should be used on coils associated with the drive. For AC coils, snubbers should
consist of a resistor and a capacitor in series across the coil. For DC coils, a free-
wheeling or flyback diode should be placed across the coil. Snubbers are typically
available from the manufacturer of the device.