LEESON SM-Plus Series Sub-Micro Inverters - Manual (Page 18)

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10.0 CONTROL WIRING
10.1 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.
Strip off 0.20 to 0.25 inches (5 to 6mm) of insulation for control wiring, and torque the terminals to 2
lb.-in. (0.2 Nm). Be careful not to overtorque the control 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.
10.2 TB-2: CIRCUIT COMMON
The TB-2 terminals are used as circuit common for the start/stop, forward/reverse, input select,
local/remote, 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.
10.3 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.
10.4 START/STOP CONTROL
There are various control schemes that allow for 2-wire and 3-wire Start/Stop circuits. Refer to the wiring
diagrams in Section 11.0 - SM-Plus
™ CONTROL WIRING DIAGRAMS.
10.5 SPEED REFERENCE SIGNALS
The drive allows for three analog speed reference inputs:
SPEED POT Connect the wiper of a speed pot to terminal TB-5, and connect the high and low end
leads to terminals TB-6 and TB-2, respectively. The speed pot can be 2.5k
Ω up to
10k Ω.
0-10 VDC Wire the positive to terminal TB-5 and the negative to terminal TB-2. TB-5 input
impedance is 120 kilohms.
4-20 mA Wire the positive to terminal TB-25 and the negative to terminal TB-2. TB-25 input
impedance is 100 ohms.