Control Wiring; Control Wiring Vs. Power Wiring; Tb-2: Circuit Common; Surge Suppression On Relays - Lenze SM004S Operating Instructions Manual

3 Installation
3.5

Control Wiring

3.5.1

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), 8770
(3-wire), or equivalent.
NOTE
Control terminals provide basic isolation (insulation per EN 61800-5-1). Protection
against contact can only be assured by additional measures e.g. supplemental insulation.
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.
3.5.2

TB-2: Circuit Common

The TB-2 terminal is used as circuit common for the analog speed reference inputs. If necessary TB-2
may be connected to chassis ground.
3.5.3

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.
3.5.4

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 3.6, SCL/SCM Control Wiring Diagrams.
3.5.5

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 2.5kΩ up to 10kΩ.
0-10 VDC Wire the positive to terminal TB-5 and the negative to terminal TB-2. TB-5 input
impedance is 120kΩ.
4-20 mA Wire the positive to terminal TB-25 and the negative to terminal TB-2. TB-25 input
impedance is 250Ω.
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Lenze 13466147 EDBSM01 v19 EN