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îš‹ Motor Overheating Protection Using PTC Thermistor Inputs
This function provides a motor overheating protection using a thermistor (PTC characteristic – Positive Tem-
perature Coefficient) which is built into the windings of each motor phase. The thermistor must be connected
to an analog input.
îš„Related Parameters
Multi-Function Analog Input (H3-09)
îš„PTC Thermistor Characteristics
Fig 6.56 shows the characteristics of the PTC thermistor temperature to the resistance value.
Fig 6.56 PTC Thermistor Temperature-Resistance Value Characteristics
îš„Operation during Motor Overheating
The operation when the motor overheats can be selected using the parameters L1-03 and L1-04. A motor over-
heat detection filter time can be set in parameter in L1-05 to prevent misdetected over heat faults.
If the motor temperature rises to the motor overheat pre-alarm level, an OH3 alarm is shown on the display
and the operation is continued according to the setting in L1-03.
If the operation is continued and the motor temperature rises further and reaches the motor overheat detection
level, an OH4 fault is shown at the display and the operation is stopped according to the setting in L1-04.
Parameter
No.
Name
Factory
Setting
Change
during
Opera-
tion
Control Methods
V/f
V/f with
PG
Open
Loop
Vector
Closed
Loop
Vector
L1-03Alarm operation selection during motor overheating 3 No AAAA
L1-04Motor overheating operation selection 1 No AAAA
L1-05 Motor temperature input filter time constant 0.20 s No AAAA
Set
Value
Function 100% of Contents
Control Methods
V/f
V/f
with
PG
Open
Loop
Vector
Closed
Loop
Vector
E Motor temperature input - Yes Yes Yes Yes
Resistance (Ohms)*
Class F
Class H
Tr: Temperature threshold value
Temperature
* The shown resistance value is for one motor phase. Normally the 3 resistors are connected in series.
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