NOTE!
If [20] is selected, 4-18 Current Limit must be set to 150%.
3.3.10.1 PTC Thermistor Connection
Figure 3.4 PTC profile
Using a digital input and 10 V as power supply:
Example: The Adjustable frequency drive trips when the
motor temperature is too high.
Parameter set-up:
Set 1-90 Motor Thermal Protection to Thermistor Trip [2]
Set 1-93 Thermistor Source to Digital Input [6]
Using an analog input and 10 V as power supply:
Example: The Adjustable frequency drive trips when the
motor temperature is too high.
Parameter set-up:
Set 1-90 Motor Thermal Protection to Thermistor Trip [2]
Set 1-93 Thermistor Source to Analog Input 54 [2]
Input
Digital/analog
Supply Voltage Threshold
Cut-out Values
Digital 10 V
< 800Ω - > 2.7 kΩ
Analog 10 V
< 3.0 kΩ - > 3.0 kΩ
NOTE!
Ensure that the chosen supply voltage follows the specifi-
cation of the thermistor element utilized.
3.3.10.2 KTY Sensor Connection
(FC 302 only)
KTY sensors are used especially in permanent magnet
servo motors (PM motors) for dynamic adjusting of motor
parameters as stator resistance (1-30 Stator Resistance (Rs))
for PM motors and also rotor resistance (1-31 Rotor
Resistance (Rr)) for asynchronous motors, depending on
winding temperature. The calculation is:
Rs
=
Rs
20°
C
x
(1 + α
cu
x
Δ
T
) Ω
where
α
cu
= 0.00393
KTY sensors can be used for motor protecting (1-97 KTY
Threshold level).
FC 302 can handle three types of KTY sensors, defined in
1-95 KTY Sensor Type. The actual sensor temperature can be
read out from 16-19 KTY sensor temperature.
Parameter Descriptions FC 300 Programming Guide
MG33MD22 - VLT
®
is a registered Danfoss trademark 3-25
3
3
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