Specifications

nominal speed at twice the nominal speed and at 0.2x the
nominal speed.
1.21.0 1.4
30
10
20
100
60
40
50
1.81.6 2.0
2000
500
200
400
300
1000
600
t [s]
175ZA052.12
f
OUT
= 2 x f
M,N
f
OUT
= 0.2 x f
M,N
f
OUT
= 1 x f
M,N
(par. 1-23)
I
MN
(par. 1-24)
I
M
Illustration 2.34 Nominal Speed
It is clear that at lower speed the ETR cuts off at lower
heat due to less cooling of the motor. In that way, the
motor is protected from overheating even at low speed.
The ETR feature is calculating the motor temperature
based on actual current and speed. The calculated
temperature is visible as a readout parameter in
DR-18 Motor Thermal in the frequency converter.
The thermistor cut-out value is > 3 kΩ.
Integrate a thermistor (PTC sensor) in the motor for
winding protection.
Motor protection can be implemented using a range of
techniques: PTC sensor in motor windings; mechanical
thermal switch (Klixon type); or Electronic Thermal Relay
(ETR).
1330
550
250
-20°C
175HA183.10
4000
3000
R
(Ω)
ϑ nominel
ϑ nominel -5°C
ϑ nominel +5°C
ϑ [°C]
Illustration 2.35 Trip
Example: Using a digital input and 24 V as power supply:
The frequency converter trips when the motor temperature
is too high.
Parameter set-up:
Set F-10 Electronic Overload to Thermistor Trip [2]
Set F-12 Motor Thermistor Input to Digital Input 33 [6]
PTC / Thermistor
OFF
ON
+24V
12 13 183732
A
27192933
B
20
GND
R<6.6 k Ω>10.8 k Ω
130BA151.11
Illustration 2.36 Digital Input and 24 V Power Supply
Example: Using a digital input and 10 V as power supply:
The frequency converter trips when the motor temperature
is too high.
Parameter set-up:
Set F-10 Electronic Overload to Thermistor Trip [2]
Set F-12 Motor Thermistor Input to Digital Input 33 [6]
PTC / Thermistor
R
OFF
ON
<800 Ω
+10V
130BA152.10
>2.7 kΩ
12 13 1837322719293320
5550
39 42 53 54
Illustration 2.37 Digital Input and 10 V Power Supply
Example: Using an analog input and 10 V as power
supply:
The frequency converter trips when the motor temperature
is too high.
Parameter set-up:
Set F-10 Electronic Overload to [2] Thermistor Trip
Set F-12 Motor Thermistor Input to [2] Analog Input 54
Do not select a reference source.
Introduction VLT® HVAC Drive FC 102 Design Guide
48 MG16C102 - Rev. 2013-08-20
2
2