Motor Components
3.1 Thermal motor protection
1PH7/3-118
Siemens AG, 2004. All rights reserved
Induction Motors, 1PH7 (APH7S) – 05.04 Edition
!
Warning
The integrated temperature sensor protects the induction motors against overload
conditions up to
4 I
0
(60
K)
and speed <> 0
Sufficient protection is no longer provided for thermally critical load situations, e.g.
for a high overload condition at motor standstill. In this case, other protective
measures must be provided, e.g. a thermal overcurrent relay.
If they exist, reduced data for standstill are specified.
3
2
0
1
0
200 300100
í
U
[°C]
I
D
= 2 mA
R [kΩ]
Fig. 3-1 Resistance characteristic as a function of the KTY 84 thermistor temperature
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