Mitsubishi Electric FR-D720-008 Installation Manuallines page 26

∗ Select a UL and cUL certified fuse with Class T fuse equivalent cut-off speed or faster with the appropriate rating for
branch circuit protection, or a UL489 molded case circuit breaker (MCCB) in accordance with the table below.
FR-D720-
Rated fuse voltage(V)
Without power factor improving reactor
Fuse Maximum
allowable rating (A)∗
With power factor improving reactor
Molded case circuit breaker (MCCB)
Maximum allowable rating (A)*
FR-D740-
Rated fuse voltage(V)
Without power factor improving reactor
Fuse Maximum
allowable rating (A)∗
With power factor improving reactor
Molded case circuit breaker (MCCB)
Maximum allowable rating (A)*
FR-D720S-
Rated fuse voltage(V)
Without power factor improving reactor
Fuse Maximum
allowable rating (A)∗
With power factor improving reactor
Molded case circuit breaker (MCCB)
Maximum allowable rating (A)*
FR-D710W-
Rated fuse voltage(V)
Without power factor improving reactor
Fuse Maximum
allowable rating (A)∗
With power factor improving reactor
Molded case circuit breaker (MCCB)
Maximum allowable rating (A)*
∗ Maximum allowable rating by US National Electrical Code. Exact size must be chosen for each installation.
∗ When using the electronic thermal relay function as motor overload protection, set the rated motor current to Pr. 9
Electronic thermal O/L relay.
Electronic thermal relay function operation characteristic
Pr. 9 = 50% setting of inverter rating*1, 2
70
30Hz
or more
*3
20Hz
60
10Hz
6Hz
0.5Hz
50
240
180
120
60
105%
52.5%
50
Inverter output current(%) (% to the rated inverter current)
Note
⋅ The internal thermal integrated value of the electronic thermal relay function is reset by inverter power reset and
reset signal input. Avoid unnecessary reset and power-OFF.
⋅ Install an external thermal relay (OCR) between the inverter and a motor when operating several motors by one
inverter, or when using a multi-pole motor or specialized motor. In this case, set 0A to the electronic thermal O/L relay
setting of the inverter. For the external thermal relay, determine the setting value in consideration of the current
indicated on the motor's rating plate and the line-to-line leakage current. Self-cooling ability of a motor is reduced at
low speed operation. Use a motor with a built-in thermal protector.
⋅ When the difference between the inverter and motor capacities is large and the setting is small, 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 the external thermal relay.
∗ Short circuit current ratings
100V class
Suitable For Use in A Circuit Capable of Delivering Not More Than 5 kA rms Symmetrical Amperes, 132 V Maximum.
200V class
Suitable For Use in A Circuit Capable of Delivering Not More Than 5 kA rms Symmetrical Amperes, 264 V Maximum.
400V class
Suitable For Use in A Circuit Capable of Delivering Not More Than 5 kA rms Symmetrical Amperes, 528 V Maximum.
-NA
-NA
-NA
-NA
Pr. 9 = 100% setting of inverter rating*2
30Hz or more
*3
20Hz
Operation range
10Hz
Range on the right of characteristic curve
6Hz Non-operation range
Range on the left of characteristic curve
0.5Hz
Characteristic when electronic thermal
relay function for motor protection is turned OFF
(when Pr. 9 setting is 0(A))
Range for
transistor
protection
100
150 200
008 014 025 042 070
240V or more
15 15 15 20 30
15 15 15 20 20
15 15 15 15 20
012 022 036 050 080
480V or more
6 10 15 20 30
6 10 10 15 25
15 15 15 15 20
008 014 025 042 070
240V or more
15 20 20 30 40
15 20 20 20 30
15 15 15 20 25
008 014 025 042
115V or more
20 20 40 60
20 20 30 50
15 15 25 40
This function detects the overload (overheat)
of the motor, stops the operation of the
inverter's output transistor, and stops the
output.
(The operation characteristic is shown on the
left.)
When using the Mitsubishi constant-torque
motor:
1) Set "1" or any of "13", "50", "53" in Pr. 71.
(This provides a 100% continuous torque
characteristic in the low-speed range.)
2) Set the rated current of the motor in Pr. 9.
∗1
When 50% of the inverter rated output current
(current value) is set in Pr. 9
∗2
The % value denotes the percentage to the
inverter rated output current. It is not the
percentage to the motor rated current.
∗3
When you set the electronic thermal relay
function dedicated to the Mitsubishi constant-
torque motor, this characteristic curve applies
to operation at 6Hz or higher.
100 165 238 318
40 60 70 80
30 50 60 70
25 40 60 80
120 160
40 70
35 60
30 40
100
60
50
40
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