Table of Contents
Advertisement
58
Thermal overload and short-circuit protection
The drive protects itself and the input and motor cables against thermal overload
when the cables are dimensioned according to the nominal current of the drive. No
additional thermal protection devices are needed.
WARNING! If the drive is connected to multiple motors, a separate thermal overload
switch or a circuit breaker must be used for protecting each cable and motor. These
devices may require a separate fuse to cut off the short-circuit current.
The drive protects the motor cable and the motor in a short-circuit situation when the
motor cable is dimensioned according to the nominal current of the drive.
Supply (AC line) cable short-circuit protection
Always protect the input cable with fuses. In networks with a short-circuit withstand
of 65 kA or less, standard gG fuses can be used. No fuses need be installed at the
drive input.
If the drive is supplied through busbars, fuses must be installed at the drive input. In
networks with a short-circuit withstand of less than 50 kA, standard gG fuses are
sufficient. If the network has a short-circuit withstand of 50 to 65 kA, aR fuses are
required.
Size the fuses according to local safety regulations, appropriate input voltage and
the rated current of the drive. Check that the operating time of the fuses is below
0.5 seconds. For fuse ratings, see
WARNING! Circuit breakers are not capable of providing sufficient protection
because they are inherently slower than fuses. Always use fuses with circuit
breakers.
Earth fault (Ground fault) protection
Both the supply unit and the inverter unit are equipped with an internal earth fault
protective function to protect the drive against earth faults in the drive, motor and
motor cable. (This is not a personal safety or a fire protection feature.) Both earth
fault protective functions can be disabled by a parameter.
See the ACQ800 Ordering Information (code: 64556568 [English], available on
request) for other available earth fault protection options.
Planning the electrical installation
ACQ800-37 Hardware Manual
Technical
data.
Advertisement
Table of Contents
