Mitsubishi Electric FR-D710W-0.1K, Instruction Manual

Page: 103 / 313

101
Selection and protection of a motor
4
P
ARAM
ETE
R
S
4.8 Selection and protection of a motor
4.8.1 Motor overheat protection (Electronic thermal O/L relay, PTC thermistor protection)
(Pr. 9, Pr. 51, Pr. 561)
∗1
These parameters can be set when Pr. 160 Extended function display selection = "0". (Refer to page 163)
∗2
When parameter is read using the FR-PU04, a parameter name different from an actual parameter is displayed.
(1) Electronic thermal O/L relay (Pr. 9)
Purpose Parameter that should be Set Refer to Page
Motor protection from overheat
Electronic thermal O/L relay
PTC thermistor protection
Pr. 9, Pr. 51, Pr. 561
101
Use the constant-torque motor Applied motor Pr. 71
104
The motor performance can be
maximized for operation in magnetic
flux vector control method.
Offline auto tuning
Pr. 71, Pr. 80,
Pr. 82 to Pr. 84,
Pr. 90, Pr. 96
106
Set the current of the electronic thermal relay function to protect the motor from overheat. This feature provides the
optimum protective characteristics, including reduced motor cooling capability, at low speed.
Parameter
Number
Name Initial Value Setting Range Description
9
Electronic thermal O/L
relay
Inverter
rated current
0 to 500A Set the rated motor current.
51
∗1
Second electronic thermal
O/L relay
∗2
9999
0 to 500A
Valid when the RT signal is ON.
Set the rated motor current.
9999 Second electronic thermal O/L relay invalid
561
∗1
PTC thermistor protection
level
9999
0.5 to 30k
Ω
Set the level (resistance value) for PTC
thermistor protection activates.
9999 PTC thermistor protection is inactive.
Electronic thermal O/L relay operation characteristic
This function detects the overload (overheat) of the
motor and trips. (The operation characteristic is shown
on the left)
Set the rated current (A) of the motor in
Pr. 9
.
(If the motor has both 50Hz and 60Hz rating and the
Pr. 3 Base frequency
is set to 60Hz, set the 1.1 times of
the 60Hz rated motor current.)
Set "0" in
Pr. 9
when you do not want to operate the
electronic thermal O/L relay, e.g. when using an external
thermal relay with the motor. (Note that the output
transistor protection of the inverter is activated (E.THT).)
When using a Mitsubishi constant-torque motor
1) Set "1" or "13", "50", "53" in any of
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 to 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 O/L relay dedicated to the Mitsubishi constant-torque motor, this characteristic curve applies to operation at 6Hz or higher.
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.
The operation time of the transistor protection thermal shortens when the
Pr. 72 PWM frequency selection setting value
increases.
Operation range
Range on the right of characteristic curve
Non-operation range
Range on the left of characteristic curve
Range for
transistor
protection
Inverter output current(%) (% to the rated inverter current)
52.5% 105%
50 100 150
60
120
180
240
50
60
70
(min) unit display
in this range
Operation time (min)
Pr. 9 = 50% setting of inverter rating*1, 2
Pr. 9 = 100% setting of inverter rating*2
(s) unit display in this range
Operation time (s)
Characteristic when electronic thermal
relay function for motor protection is turned OFF
(when
Pr. 9
setting is 0(A))
6Hz
20Hz
10Hz
6Hz
0.5Hz
30Hz or more
*3
30Hz
or more
*3
20Hz
10Hz
0.5Hz
200