Output Circuit And Motor Protection - Emerson Unidrive M201 Installation Manual

The nominal output cable sizes in section 2.4 Ratings on page 13 assume that the motor
NOTE
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 13. Failure
to observe this requirement will cause risk of fire.
WARNING
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.
4.7.1 Main AC supply contactor
The recommended AC supply contactor type is AC1.
4.8

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, Pr 00.046
(Pr 00.006 on Unidrive M200 to M400) Motor rated current must be set to suit the motor.
Pr 00.046 (Pr 00.006 on Unidrive M200 to M400) Motor rated current must be set correctly
to avoid a risk of fire in the event of motor overload.
WARNING
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.
4.8.1 Motor cable types
Since capacitance in the motor cable causes loading on the output of the drive, ensure the cable
length does not exceed the values given in Table 5-23 Maximum motor cable lengths on page 107.
Use 105 °C (221 °F) (UL 60/75 °C temp rise) PVC-insulated cable with copper conductors having a
suitable voltage rating, for the following power connections:
• AC supply to external EMC filter (when used)
• AC supply (or external EMC filter) to drive
• Drive to motor
• Drive to braking resistor
Unidrive M / HS Frame 7 to 10 Power Installation Guide
Issue Number: 5
63