Unidrive M/HS Frame 5 to 6 Power Installation Guide 57
Issue Number: 9
Safety information Product information Mechanical installation
Electrical installation
Technical data UL listing information
4.8 Ratings
See section 2.4 Ratings on page 17.
Maximum continuous input current
The values of maximum continuous input current are given to aid the selection of cables and fuses.
These values are stated for the worst case condition with the unusual combination of stiff supply with
high imbalance. The value stated for the maximum continuous input current would only be seen in
one of the input phases. The current in the other two phases would be significantly lower.
The values of maximum input current are stated for a supply with a 2 % negative phase-sequence
imbalance and rated at the maximum supply fault current given in section 2.4 Ratings on page 17.
The nominal cable sizes given in section 2.4 Ratings on page 17 are only a guide. Refer to local
wiring regulations for the correct size of cables. In some cases a larger cable is required to avoid
excessive voltage drop.
A fuse or other protection must be included in all live connections to the AC supply.
Fuse types
The fuse voltage rating must be suitable for the drive supply voltage.
4.8.1 Main AC supply contactor
The recommended AC supply contactor type for size 5 and 6 is AC1.
4.9 Output circuit and motor protection
The output circuit has fast-acting electronic short-circuit protection which limits the fault current to
typically no more than five times the rated output current, and interrupts the current in approximately
20 µs. No additional short-circuit protection devices are required.
The drive provides overload protection for the motor and its cable. For this to be effective,
Rated Current (00.046) must be set to suit the motor.
There is also provision for the use of a motor thermistor to prevent over-heating of the motor, e.g. due
to loss of cooling.
The nominal output cable sizes in section 2.4 Ratings on page 17 assume that the motor
maximum current matches that of the drive. Where a motor of reduced rating is used the
cable rating may be chosen to match that of the motor. To ensure that the motor and cable
are protected against over-load, the drive must be programmed with the correct motor
rated current.
Fuses
The AC supply to the drive must be installed with suitable protection against overload and
short-circuits. Nominal fuse ratings are shown in section 2.4 Ratings on page 17. Failure
to observe this requirement will cause risk of fire.
Rated Current (00.046) must be set correctly to avoid a risk of fire in the event of motor
overload.
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