Motor Protection; Motor Overload Detection - Saftronics FP5/GP5 Series Technical Manual

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6.7

Motor Protection

6.7.1.

Motor Overload Detection

The Inverter protects against motor overload with a built-in electronic Thermal Overload Relay.
§
Motor Rated Current (n032)
Set to the rated current value shown on the motor nameplate.
§
Motor Overload Protection Selection (n033)
Setting
The electronic Thermal Overload Relay function monitors motor temperature, based on Inverter output current and
time, to protect the motor from overheating. When electronic Thermal Overload Relay is enabled, an OL1 error
occurs, shutting OFF the Inverter output and preventing excessive overheating in the motor.
When operating with one Inverter connected to one motor, an external Thermal Overload Relay is not needed.
When operating several motors with one Inverter, install a Thermal Overload Relay on each motor. In this case, set
constant n033 to 0.
§
Standard Motor and Inverter Motor
Induction motors are classified as standard motors or Inverter motors, based on their cooling capabilities. Therefore,
the motor overload function operates differently between these two motor types.
Firmware – S2011 and S3012
Revision: 1 (9/98)
Electronic Thermal Characteristics
0 No protection
1 Standard motor (time constant 8 minutes) (Factory setting)
2 Standard motor (time constant 5 minutes)
3 Inverter motor (time constant 8 minutes)
4 Inverter motor (time constant 5 minutes)
Table 17 Overload Curves
Cooling Effect
Effective when operated
at 50/60 Hz from
commercial power supply.
For low speed operation, torque must be
limited in order to stop motor temperature rise.
Effective even when
operated at low speed
(approximately 6 Hz).
Use an inverter motor for continuous
operation at low speed.
Chapter 6: Programming Features
Torque Characteristics
Operation Frequency (Hz)
Base Frequency 60 Hz
(V/f for 60 Hz, 220 V Input Voltage)
Operation Frequency (Hz)
Base Frequency 60 Hz
(V/f for 60 Hz, 220 V Input Voltage)
57
Electronic Thermal
Overload
OL1 error (motor overload
protection) occurs when
continuously operated at
50/60 Hz or less at 100%
load.
Electronic Thermal
Overload Relay protection
not enabled even when
continuously operated at
50/60 Hz or less at 100%
load.
© Saftronics, Inc.