Download  Print this page

Selection And Protection Of A Motor; Motor Overheat Protection (electronic Thermal O/l Relay, Ptc Thermistor Protection) (pr. 9, Pr. 51, Pr. 561) - Mitsubishi Electric FR-F700PJ Instruction Manual

Air-conditioning inverter.
Hide thumbs

Advertisement

4.9

Selection and protection of a motor

Purpose
Motor protection from overheat
Use the constant-torque motor
The motor performance can be
maximized for operation in magnetic
flux vector control method.
4.9.1
Motor overheat protection (Electronic thermal O/L relay, PTC thermistor protection)
(Pr. 9, Pr. 51, Pr. 561)
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
Name
Number
Electronic thermal O/L
9
relay
51
Second electronic thermal
V/F
V/F
V/F
O/L relay
GP
GP
GP
MFVC
MFVC
MFVC
PTC thermistor protection
561
level

The above parameters can be set when Pr. 160 Extended function display selection = "0". (Refer to page 197)

Performing IPM parameter initialization automatically sets the rated current of the IPM motor. (Refer to page 85)

When parameter is read using the FR-PU04, a parameter name different from an actual parameter is displayed.
(1)
Electronic thermal O/L relay operation under general-purpose motor control (Pr. 9)
Electronic thermal O/L relay operation characteristic
Pr. 9 = 50% setting of inverter rating*1, 2
70
30Hz
or more
*3
20Hz
60
10Hz
6Hz
50
0.5Hz
240
180
120
60
105%
52.5%
50
Inverter output current (%)
(% to the rated inverter current)

When 50% of the rated inverter output current (current value) is set to Pr. 9

The % value denotes the percentage to the rated inverter output current. It is not the percentage to the rated motor current.

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.
(Refer to page 123 for the operation characteristic.)
NOTE
 Internal accumulated heat value of the electronic thermal relay function is reset by inverter power reset and reset
signal input. Avoid unnecessary reset and power-OFF.
 When multiple motors are operated by a single inverter, protection cannot be provided by the electronic thermal
function. Install an external thermal relay to each motor.
 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 an external thermal relay.
 The operation time of the transistor protection thermal shortens when the Pr. 72 PWM frequency selection setting value
increases.
Electronic thermal O/L relay
PTC thermistor protection
Applied motor
Offline auto tuning
Initial Value
Rated
inverter current
9999
9999
Pr. 9 = 100% setting of inverter rating*2
30Hz or more
*3
20Hz
Operation range
10Hz
Range on the right of
6Hz
characteristic curve
0.5Hz
Non-operation range
Range on the left of
characteristic curve
Characteristic when
electronic thermal
relay function for motor
protection is turned OFF
(when Pr. 9 setting is 0(A))
Range for
transistor
protection
100 120
150
Selection and protection of a motor
Parameter that should be Set
Pr. 9, Pr. 51, Pr. 561
Pr. 71
Pr. 71, Pr. 80, Pr. 82 to Pr.
84, Pr. 90, Pr. 96
Setting Range
0 to 500A
Set the rated motor current.
Valid when the RT signal is ON.
0 to 500A
Set the rated motor current.
9999
Second electronic thermal O/L relay invalid
Set the level (resistance value) for PTC
0.5 to 30k
thermistor protection activates.
9999
PTC thermistor protection is inactive.
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 functions (E.THT).)
 When using a Mitsubishi constant-torque motor
1) Set "1" or "13", "50", "53" in any of Pr. 71. (This
provides
a
characteristic in the low-speed range.
2) Set the rated current of the motor in Pr. 9.
Refer to Page
119
123
125
Description
GP
GP
GP
V/F
V/F
V/F
MFVC
MFVC
MFVC
100%
continuous
torque
119
4

Advertisement

Table of Contents

   Also See for Mitsubishi Electric FR-F700PJ

Comments to this Manuals

Symbols: 0
Latest comments: