If a transformer primary winding operates at 240v, the
secondary at 120v and the load is 1500w & the transformer
is rated at 92% efficient, what's the current flowing
through the primary winding of the transformer? What is the
formula for finding this?

We have .ht motor which is 60Hz.we run on 50Hz.so that it's speed reduce
but we had one prob.that motor winding temp increase up to 135 deg.we
want reduce this temp.what to do?we arrange ext.cooling fan but not much
effect.we want reduce this temp. Inhouse without affecting much.cost. also
don't want reWINDING OF MOTOR?

For these 2 devices what their power ratings are ?
1) single phase : AC 220V & starting amps 3Amps (i.e.
starting torque) and the stabilized amps 2A ... For deep
freezer
2) single phase : AC 220V & starting amps 2.7Amps (i.e.
including the starting torque of a CRT monitor) and the
stabilized amps 1 Amps
thanks

why the Parameters : Base Voltage & Maximum Voltage can't be
equal in value in a VFD (Variable Frequency Drive) ?
How much the base voltage would be lower than the maximum
voltage ? If 400 V is the 3 phase output of a VFD ... then
what should be the base voltage ?
thanks a lot

I am getting diesel genset 62 kv for my house
In addition there are 6 meters of 11kv for the house
Lift also being installed for house plot sise 200sq yds
total 4 + 2 foloors
I want to know how much earthing required how deep it should be

wht is the purpose of the earth electrode other then earthing

152

HELLO EVERYONE, I RECENTLY HAVE FOUND ONE PROBLEM, I WAS
TAKING NO LOAD TRIAL OF AN HT MOTOR 920 MOTOR , 1440 RPM ,
6.6 KV, WITH AUTO TRANSFORMER. AT 450 V, LOAD WAS 40 AMP
AND SPEED WAS 250 RPM. BUT AS WE INCREASE VOLTAGE FROM 450
TO 480V, LOAD BECOME 41 AND SPEED REDUCED TO SOME RPM . SO
WHICH PHENOMENON ACTED HERE FOR REDUCING SPEED.?? AND IS IT
HAPPENING ALWAYS OR IT IS RARE? I ALSO HAVE FACED SUCH
PROBLEM WITH FEW LT MOTOR ALSO.

105

Anyone who can recommend an equivalent to Envirotemp FR3 of
Cooper?

159

what is the mechanism of operation of brushless dc motor
why is it more wexpensive then ordinary permanent magnet
motors