Settings - Siemens Siprotec 7UM611 Manual

In Figure 2-56, the motor is also restarted twice in warm condition, but the pause
between the restart attempts is longer than in the first example. After the second
restart attempt, the motor is operated at 90 % nominal current. After the shutdown fol-
lowing the first startup attempt, the thermal profile is "frozen". After the temperature
leveling time (1 min), the rotor cools down with the time constant τ
5 · 204 s = 1020 s. During the second restart, the starting current causes a tempera-
ture rise, whereas the subsequently flowing load current of 0.9 · I/I
RUNNING reduces the temperature. This time, the time constant τ
· 204 s = 408 s is effective.
The fact that the restart limit is exceeded for a short time does not mean a thermal
overload. It rather indicates that a thermal overload of the rotor would result if the
motor were shut down immediately and restarted.
Figure 2-56

2.25.3 Settings

Addr. Parameter
6601 RESTART INHIBIT
6602 IStart/IMOTnom
6603 T START MAX
6604 T EQUAL
6606 MAX.WARM STARTS
6607 #COLD-#WARM
7UM61 Manual
C53000-G1176-C127-3
Two Warm Restarts Followed by Continuous Running
Setting Options
OFF
ON
Block relay
1.5 .. 10.0
3.0 .. 320.0 sec
0.0 .. 320.0 min
1 .. 4
1 .. 2
2.25 Restart Inhibit for Motors (ANSI 66, 49Rotor)
Default Setting
OFF Restart Inhibit for Motors
4.9 I Start / I Motor nominal
8.5 sec Maximum Permissible Starting
Time
1.0 min Temperature Equalization Time
2 Permissible Number of Warm
Starts
1 Number of Cold Starts - Warm
Starts
· Kτ at STOP ≈
L
Kτ at
N Motor
· Kτ at STOP = 2
L
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