Implementing Thermal Overload And Short-Circuit Protection; Protecting The Drive And Input Power Cable In Short-Circuits; Protecting The Motor And Motor Cable In Short-Circuits; Protecting The Drive And The Power Cables Against Thermal Overload - ABB ACS880-37 Hardware Manual

88 Guidelines for planning the electrical installation
Implementing thermal overload and short-circuit
protection

Protecting the drive and input power cable in short-circuits


The drive is equipped with internal AC fuses as standard. Protect the input cable with
fuses or a suitable circuit breaker. Size the input cable fuses according to the instructions
given in chapter Technical
situations, restrict drive damage and prevent damage to adjoining equipment in case of a
short-circuit inside the drive.

Protecting the motor and motor cable in short-circuits


The drive protects the motor cable and motor in a short-circuit situation when the motor
cable is sized according to the nominal current of the drive. No additional protection
devices are needed.

Protecting the drive and the power 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.
An optional ground fault monitoring device (+Q954) is available for IT (ungrounded)
systems. The option includes a ground fault indicator on the drive cabinet door.
data. The fuses will protect the input cable in short-circuit