I have a 3-phase motor (1.5 HP, 400V)and wnt to operate it using a single phase source (220V). if i was to use the capacitor for this converstion how can i determine the capacitance.
thanks for every ..
i 've got good informations ,,
but i have two motors with the same power and the same source (transformer) and only one of them that has this problem ... the other startup normally with 0.3 sec time delay while the other needs about 1.3 sec, and in the past it was starting up...
hello laundry...
if we have a motor (400V, 200KW, delta) with high insulation resistance (2G ohm), the earth leakage relay gives a trip signal at the starting of the motor. if i increase the time delay (0.3 sec) to 1 sec the motor start normally and no trip signal appears. so what can make the...
first .. thank u all
i have one more question ...
for the unbalanced line currents ... the magnetude of the current will be different also their summation is zero ..
** so the phase shift angle between the line currents will not be the same (120), isn't it? **
if there are 3 line (3 phase power system)passing through a ring transformer (core balanced CT) and feeding unbalanced delta load. Does the core balanced CT get an output (secondary winding) related to this imbalanced current?.
or it will only get an output in the case of earth leakage?.
if the is unbalance in the current of the motor (delta) for any reason and there is no ground fault .... the summation of the current will be zero and the output of the core balanced CT will be zero ... isn't it?
hi Marke
ur analysis is what i was thinking for this problem .. as i was say that when a motor spends a long time out of service, this may form a moister inside it ... specially when there is no space heater inside it.
when restarting the motor after running for a long time it doesn't tripped...
the motor was working normally before 6 monthes ... it was working on this setting normally .. and there are similar motors and others with greater power working on setting I=0.3A ... t=0.3sec without any problems ...
maintenance was done on this motor ... and a calibration check for the earth...
i want to explain more ..
a sqirel cage induction motor 400v , delta winding, 110kw.
this motor protected by an earth fault relay with a core balanced CT. when measuring the isolation resistance of the motor, it founds high (>1 G ohm for 1 min),but at the start of the motor the earth fault relay...
