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Functions
2.7 Motor Protection (Motor Starting Protection 48, Motor Restart Inhibit 66, Load Jam Protection)
B) Above the thermal restarting limit:
1.
A startup brings the machine from load operation into a temperature range far above the thermal restarting
limit and the machine is stopped. The minimum inhibit time and the equilibrium time are started and „66
TRIP" is reported. The temperature cool-down below the restarting limit takes longer than 4310 and T
MIN. INHIBIT and 4304 T Equal, so that the time passing until the temperature falls below the tem-
perature limit is the decisive factor for clearing the message „66 TRIP". The thermal replica remains "fro-
zen" while the equilibrium time expires (see Figure 2-41, to the left).
2.
A startup brings the machine from load operation into a temperature range just above the thermal restarting
limit and the machine is stopped. The minimum inhibit time and the equilibrium time are started and „66
TRIP" is reported. Although the temperature soon falls below the restarting limit, the blocking „66 TRIP"
is preserved until the equilibrium time and the minimum inhibit time have expired (see Figure 2-41, to the
right).
Figure 2-41
142
Starting up according to examples B.1 and B.2
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A5, Release date 11.2012
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