Mitsubishi Electric FR-S540E-0.4K-EC Instruction Manual page 78

4. Motor overload protection
These inverters provide solid state motor overload protection.
Set Pr. 9 using the following instructions,
(Pr. 9 "electronic thermal O/L relay").
<Setting>
Set the rated current [A] of the motor in Pr. 9.
Setting "0" in Pr. 9 disables electronic thermal relay function (motor protective func-
tion). (The protective function of the inverter is activated.)
When using a Mitsubishi constant-torque motor, first set "1" in Pr. 71 "applied motor".
(This provides a 100% continuous torque characteristic in the low-speed range.)
Then, set the rated current of the motor in Pr. 9 "electronic thermal O/L relay".
CAUTION
When two or more motors are connected to the inverter, they cannot be protected by
the electronic thermal relay function. Install an external thermal relay to each motor.
When a difference between the inverter and motor capacities is large and the setting
becomes less than half amount of the inverter rated current, the protective
characteristics of the electronic thermal relay function will be deteriorated. In this case,
use an external thermal relay.
A special motor cannot be protected by the electronic thermal relay function.
Use an external thermal relay.
Reference: Motor overload protection characteristics
50% setting 100% setting
(Note 1, 2) (Note 2)
240
180
120
60
0 50 100
Inverter output current (%)
(% to rated inverter output current)
30Hz or higher
(Note 3)
20Hz
10Hz
Electronic thermal relay
function for transistor
protection
150 180200
Protection activating range
Range on the right of characteristic curve
Normal operating range
Range on the left of characteristic curve
(Note 1) When you set the 50% value (current
value) of the rated inverter output current.
(Note 2) The % value denotes the percentage of
the current value to the rated inverter
output current, not to the rated motor current.
(Note 3) This characteristic curve will be described
even under operation of 6Hz or higher
when you set the electronic thermal relay
function dedicated to the Mitsubishi
constant-torque motor.
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