44 Unidrive M100-101 Quick Start Guide
Issue Number: 6
10.7 cUL requirements for frame size 4
For frame size 4, models Mxxx-042 00133A, Mxxx-042 00176A, Mxxx-044 00135A and Mxxx-044
00170A, transient surge suppression shall be installed on the line side of this equipment and shall be
rated 480 Vac (phase to ground), 480 Vac (phase to phase), suitable for overvoltage category III, and
shall provide protection for a rated impulse withstand voltage peak of 6 kV and a clamping voltage of
maximum 2400 V.
Mxxx denotes M100, M101, M200, M201, M300 or M400.
10.8 Motor overload protection
All models 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 within instructions/manual for the product. Maximum current overload is
dependent on the values entered into the current limit parameters (Motoring Current Limit (04.005),
Regenerative Current Limit (04.006) and Symmetrical Current Limit (04.007) entered as percentage)
and the Motor Rated Current (00.006) entered in amperes). The duration of the overload is
dependent on Motor Thermal Time Constant (04.015) variable up to a maximum of 3000 seconds.
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 product can be connected to a
motor thermistor to protect the motor, in the event of a motor cooling fan failure.
10.9 Motor overspeed protection
The drive is installed with solid state motor overspeed protection.
However, this feature does not provide the level of protection provided by an independent, high-
integrity overspeed protection device and should not be considered as a safety function.
10.10 Thermal memory retention
Drives incorporate thermal memory retention that complies fully with the requirements of UL508C.
The drive is provided with motor load and speed sensitive overload protection with thermal memory
retention that complies with the US National Electrical Code (NFPA 70) clause 430.126 and
Underwriters Laboratories Standard UL508C, clause 20.1.11 (a). The purpose of this protection is to
protect both drive and motor from dangerous overheating in the event of repeated overload or failure
to start, even if the power to the drive is removed between overload events.
For full explanation of the thermal protection system, refer to the Drive User Guide for further
information.
In order to comply with UL requirements for thermal memory retention, it is necessary to set the
Thermal Protection Mode (04.016) to zero; and the Low Frequency Thermal Protection Mode
(04.025) must be set to 1 if the drive is operated in Heavy Duty mode.
Alternatively, an external thermal sensor or switch may be used as a means of motor and drive
overload protection that complies with the requirements of UL508C, clause 20.1.11 (b). This
protection method is particularly recommended where independent forced cooling of the motor is
used, because of the risk of overheating if the cooling is lost.
External thermal sensor
The drive is provided with a means to accept and act upon a signal from a thermal sensor or switch
imbedded in the motor or from an external protective relay. Refer to the Drive User Guide for further
information.
Unidrive M100 101 Quick Start Guide English Iss6.book Page 44 Wednesday, September 9, 2015 4:07 PM
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