Lenze SCD Series - 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 6 mm) of insulation for control wiring, and torque the control
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 AND TB-4
The TB-2 terminal is the circuit common for the analog input and analog output functions. If necessary
TB-2 may be connected to chassis ground.
The TB-4 terminal is the reference for all of the digital inputs (TB-1, 12, 13A, 13B, 13C). On
standard SCD drives, TB-4 is at zero volt potential. Therefore, the digital inputs are active-low.
10.3 SURGE SUPPRESION 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 - SCD 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 (rated 2.5k
Ω
up to 10k
Ω)
to terminal TB-5/25, and
connect the high and low end leads to terminals TB-11 and TB-2, respectively.
0-10 VDC Wire the positive to terminal TB-5/25 and the negative to terminal TB-2. TB-5/25
input impedance is 120 kilohms when programmed for 0-10 VDC input.
4-20 mA Wire the positive to terminal TB-5/25 and the negative to terminal TB-2. TB-5/25
input impedance is 100 ohms when programmed for 4-20 mA.