Electrical Installation; Motor Overload Protection And Thermal Memory Retention; Electrical Supply - Emerson Unidrive M201 Installation Manual

6.6

Electrical Installation

TERMINAL TORQUE
Terminals must be tightened to the rated torque as specified in the Installation Instructions. Refer to
section 3.10 Terminal size and torque settings on page 44 for further information.
WIRING TERMINALS
Drives must be installed using cables rated for 75 °C operation, copper wire only.
UL Listed closed-loop connectors sized according to the field wiring shall be used for all field wiring
connections. Refer to section 3.10 Terminal size and torque settings on page 44 for further
information.
BRANCH CIRCUIT PROTECTION
The fuses and circuit breakers required for branch circuit protection are contained in the Installation
Instructions. Refer to section 5.1.20 Input current, fuse and cable size ratings on page 103
OPENING OF BRANCH CIRCUIT
Opening of the branch-circuit protective device may be an indication that a fault has been
interrupted. To reduce the risk of fire or electric shock, the equipment should be examined and
replaced if damaged. If burnout of the current element of an overload relay occurs, the complete
overload relay must be replaced.
Integral solid state short circuit protection does not provide branch circuit protection. Branch circuit
protection must be provided in accordance with the National Electrical Code and any additional local
"codes".
6.7

Motor overload protection and thermal memory retention

All drives incorporate internal overload protection for the motor load that does not require the use of
an external or remote overload protection device.
The protection level is adjustable and the method of adjustment is provided in the Control User
Guide. Maximum current overload is dependent on the values entered into the current limit
parameters (motoring current limit, regenerative current limit and symmetrical current limit entered as
percentage) and the motor rated current parameter (entered in amperes).
The duration of the overload is dependent on motor thermal time constant. The time constant is
programmable. The default overload protection is set such that the product is capable of 150 % of the
current value entered into the motor rated current parameter for 60 seconds.
The drives are provided with user terminals that can be connected to a motor thermistor to protect
the motor from high temperature, in the event of a motor cooling fan failure.
The method of adjustment of the overload protection is provided in the Installation Instructions
shipped with the product.
All models are provided with thermal memory retention.
6.8

Electrical supply

The drives are suitable for use on a circuit capable of delivering not more than 100,000 RMS
Symmetrical Amperes, at rated voltage when protected by fuses as specified in the Installation
Instructions.
Some smaller drives are suitable for use on a circuit capable of delivering not more than 10,000 RMS
Symmetrical Amperes, at rated voltage when protected by circuit breakers as specified in the
Installation Instructions.
Unidrive M / HS Frame 7 to 10 Power Installation Guide
Issue Number: 5
117