Lenze SCF frequency inverter - Manual (Page 20)

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Lenze 13466146 EDBSF01 v24 EN
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) or
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 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.
3.5.2 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.
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 - SCF 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 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.