Electrical installation: AC input, motor and brake 55
Motor circuit contactors
If required by local codes or for safety reasons, an M-Contactor (motor circuit
contactor) can be installed to provide a physical disconnection of the motor windings
from the MicroFlex e150 (see Motor connections on page 52). Opening the M-
Contactor ensures that the MicroFlex e150 cannot drive the motor, which might be
necessary during equipment maintenance or similar operations.
If an M-Contactor is installed, the MicroFlex e150 must be disabled at least 20 ms
before the M-Contactor is opened. If the M-Contactor is opened while the
MicroFlex e150 is supplying voltage and current to the motor, the MicroFlex e150 can
be damaged. Incorrect installation or failure of the M-Contactor or its wiring can result
in damage to the MicroFlex e150.
Ensure that shielding of the motor cable is continued on both sides of the M-
Contactor, as shown in the previous diagram.
Sinusoidal filter
A sinusoidal filter is used to provide a better quality waveform to the motor, reducing
motor noise, temperature and mechanical stress. It will reduce or eliminate harmful
dV/dt values (voltage rise over time) and voltage doubling effects which can damage
motor insulation. This effect occurs most noticeably when using very long motor
cables, for example 30.5 m (100 ft) or more. ABB servo motors intended to be used
with drives are designed to withstand the effects of large dV/dt and overvoltage
effects. However, if very long motor cables are unavoidable and are causing
problems, then a sinusoidal filter can be beneficial.
Motor brake connection
A rotary motor might require a brake. The brake prevents the uncontrolled release of
suspended or tensioned loads when power to the motor is removed or disconnected,
e.g. by a motor circuit contactor. Contact your local supplier for details of appropriate
brakes.
You can wire a motor's brake, via relays, to digital outputs on connector X3 or OPT1
(see Connections - front panel on page 23, and Connections - top panel on page 24).
This provides a way for the MicroFlex e150 to control the motor's brake. A typical
circuit is shown in the following diagram:
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