H26
PTC / NTC Thermistor (Mode)
H27
PTC / NTC Thermistor (Level)
These function codes protect the motor from overheating or output an alarm signal using the PTC
(Positive Temperature Coefficient) thermistor or NTC (Negative Temperature Coefficient)
thermistor embedded in the motor.
■
PTC thermistor (Mode) (H26)
Selects the function operation mode (protection or alarm) for the PTC thermistor as shown below.
Data for H26
Action
0
Disable
1
Enable
When the voltage sensed by the PTC thermistor exceeds the detection level,
the motor protective function (alarm
OH4
) is triggered, causing the inverter
to enter an alarm stop state.
2
Enable
When the voltage sensed by the PTC thermistor exceeds the detection level,
a motor alarm signal is output but the inverter continues running.
You need to assign the motor overheat protection
THM
to one of the digital
output terminals beforehand (function code data = 56), by which a
temperature alarm condition can be indicated to the external equipment.
3
Enable
When the voltage sensed by the NTC thermistor exceeds the detection
level, the motor protective function (alarm
OH4
) is triggered, causing the
inverter to enter an alarm stop state.
■
PTC thermistor (Level) (H27)
Specifies the detection level for the temperature (expressed in voltage) sensed by PTC thermistor.
- Data setting range: 0.00 to 5.00 (V)
The temperature at which the overheating protection is to be activated depends on the characteristics
of the PTC thermistor. The internal resistance of the thermistor will significantly change at the alarm
temperature. The detection level (voltage) is specified based on the change of internal resistance.
Suppose that the resistance of PTC thermistor at alarm temperature is Rp, the detection (voltage)
level V
v2
is calculated by the equation below. Set the resulting value of V
v2
to function code H27.
Replace the internal resistance of the PTC thermistor at the alarm temperature with Rp to obtain V
v2
.
(V)
10.5
Rp
27000
R
×
p
V2
V
+
=
2-92
Summary of Contents for Frenic lift
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