TOSHIBA
6F9EOlll
Where
6R:
temperature rise of the rotor at time t CC)
~9
S: temperature rise of the
stator
at time t (C)
TR:
heating time constant of the motor (minute) (set value)
(2)
When the load current is higher than 2.5 times the rated current
(2.5 x IN
<
I(t)):
From the heating characteristic during locking that isdetermined by the
motor starting current (1st) and the allowable locking time. the temper-
ature rise of the rotor is simulated.
When at time
0
the rotor is locked, then
l(t),
1
BR(t)
=
eR(O)
+
(,st
) .
-
.
TSC
elm.
t
. . . . . . . . . . . . . ...(5)
Where 0 R(t): temperature rise of the rotor at time t
('C)
OR(O):
temperature rise of the rotor before the rotor is
locked (C)
In*
load current at time t (A)
1st:
_
starting current (A) (setting value)
TSC:
allowable locking time in the cold state
(set)
(setting value)
9
RM:
allowable temperature rise of the rotor CC)
(fixed at
2OO'C)
When
OR(t)
=
9~
the trip operation is carried out.,
The operation characteristic (operating time) in the locked state varies
depending on the heated condition of the motor and the conducting current.
-
110
-
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