2.25 Restart Inhibit for Motors (ANSI 66, 49Rotor)
155
7UM61 Manual
C53000-G1176-C127-3
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 Ï„
L
· Kτ at STOP ≈
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
N Motor
KÏ„ at
RUNNING reduces the temperature. This time, the time constant Ï„
L
· Kτ at STOP = 2
· 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 Two Warm Restarts Followed by Continuous Running
2.25.3 Settings
Addr. Parameter Setting Options Default Setting Comments
6601 RESTART INHIBIT OFF
ON
Block relay
OFF Restart Inhibit for Motors
6602 IStart/IMOTnom 1.5 .. 10.0 4.9 I Start / I Motor nominal
6603 T START MAX 3.0 .. 320.0 sec 8.5 sec Maximum Permissible Starting
Time
6604 T EQUAL 0.0 .. 320.0 min 1.0 min Temperature Equalization Time
6606 MAX.WARM STARTS 1 .. 4 2 Permissible Number of Warm
Starts
6607 #COLD-#WARM 1 .. 2 1 Number of Cold Starts - Warm
Starts
www . ElectricalPartManuals . com
To Next Page
Loading...
Need help?
General