Siemens SIPROTEC 7SK80 User Manual

Functions
2.7 Motor Protection (Motor Starting Protection 48, Motor Restart Inhibit 66, Load Jam Protection)
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
124
Threshold Values "cold" / "warm" Motor
Parameter 4106 TEMP.COLD MOTOR determines the threshold value. It is derived from the number of cold
(n
cold
) and warm (n
warm
) motor startups.
Unless specified otherwise, three cold and two warm startups (n
cold
= 3; n
warm
= 2) will be sufficient. These are
typical motor data. The limit value is thus derived:
A recommended setting value with consideration of a safety margin for TEMP.COLD MOTOR = 25%.
Should the technical data of the motor make reference to four cold and two warm startups (n
cold
= 4; n
warm
= 2),
the following limit value can be determined:
The setting value should fall below the limit value. A value of 40% is recommended for that purpose.
Note
Overload protection curves are also effective during motor starting conditions. However, the thermal profile
during motor starting is constant. Parameter I MOTOR START at address 1107 limits the working range of the
overload protection to larger current values.

Siemens SIPROTEC 7SK80 Specifications

General

Brand	Siemens
Model	SIPROTEC 7SK80
Category	Protection Device
Language	English