Protecting The Drive And The Input Power And Motor Cables Against Thermal Overload; Protecting The Motor Against Thermal Overload; Protecting The Drive Against Ground Faults; Residual Current Device Compatibility - ABB ACS880-07 Hardware Manual

Protecting the drive and the input power and motor cables against

thermal overload
The drive protects itself and the input and motor cables against thermal overload when the
cables are sized according to the nominal current of the drive. No additional thermal
protection devices are needed.
WARNING! If the drive is connected to multiple motors, use a separate circuit
breaker or fuses for protecting each motor cable and motor against overload. The
drive overload protection is tuned for the total motor load. It may not trip due to an
overload in one motor circuit only.

Protecting the motor against thermal overload


According to regulations, the motor must be protected against thermal overload and the
current must be switched off when overload is detected. The drive includes a motor
thermal protection function that protects the motor and switches off the current when
necessary. Depending on a drive parameter value, the function either monitors a
calculated temperature value (based on a motor thermal model) or an actual temperature
indication given by motor temperature sensors. The user can tune the thermal model
further by feeding in additional motor and load data.
The most common temperature sensors are:
•
motor sizes IEC180...225: thermal switch, eg, Klixon
•
motor sizes IEC200...250 and larger: PTC or Pt100.
See the firmware manual for more information on the motor thermal protection, and the
connection and use of the temperature sensors.

Protecting the drive against ground faults

The drive is equipped with an internal ground fault protective function to protect the unit
against ground faults in the motor and motor cable in TN (grounded) networks. This is not
a personnel safety or a fire protection feature. The ground fault protective function can be
disabled with a parameter, refer to the firmware manual.
Optional ground fault monitoring device (+Q954) is available for IT (ungrounded) systems.
The option includes a ground fault pilot light on the drive cabinet door.

Residual current device compatibility


The drive is suitable to be used with residual current devices of Type B.
Note: The EMC filter of the drive includes capacitors connected between the main circuit
and the frame. These capacitors and long motor cables increase the ground leakage
current and may cause fault current circuit breakers to function.

Implementing the emergency stop function

The drive can be equipped with category 0 and 1 emergency stop functions (options
+Q951, +Q952, +Q963 and +Q964). For safety reasons, install the emergency stop
devices at each operator control station and at other operating stations where emergency
stop may be needed.
Guidelines for planning the electrical installation 79