Settings Of The Restart Inhibit For Motors - Siemens Siprotec 7UM62 Manual

2.33.2.1 Settings of the Restart Inhibit for Motors

Addr. Setting Title
6601 RESTART INHIBIT
6602 IStart/IMOTnom
6603 T START MAX
6604 T EQUAL
6606 MAX.WARM
STARTS
6607 #COLD-#WARM
7UM62 Manual
C53000-G1176-C149-3
In Figure 2-107, 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
following the first starting attempt, the thermal profile is "frozen". After the temperature
equilibrium time (1 min) the rotor cools down with the time constant
τ
⋅ Kt at STOP ≈ 5 ⋅ 204 s = 1020 s. During the second restart, the starting current
L
causes a temperature rise, whereas the subsequently flowing on-load current of
0.9 ⋅ I/I
reduces the temperature. This time, the time constant
N Motor
τ
⋅ Kt at RUNNING = 2 ⋅ 204 s = 408 s is effective.
L
The fact that the restarting limit is exceeded for a short time does not mean a thermal
overload. It rather signals that a thermal overload of the rotor would arise if the motor
were shut down immediately and restarted.
1st startup
p.u.
1.0
0.8
0.6
0.4
0.2
0
200
Figure 2-107 Two Warm Restart Followed by Continuous Running
Setting Options
OFF
ON
Block relay for trip com-
mands
1.5..10.0
3.0..320.0 sec
0.0..320.0 min
1..4
1..2
Restart Inhibit for Motors (ANSI 66, 49Rotor)
2nd startup
400 600
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
Temperature in p.u.
Restarting limit
Motor current in I/I
N
800 1000 t/s
Comments
223