Electrical Questions

Insufficient information.

Look on motor nameplate or data sheet or measure it.

Off, or on? No load off...0A

Single phase or three phase?

Voltage?

Frequency?

Service Factor?

Horsepower?

A lot less than 60.

It can be anywhere from 0 to 60 amperes of current depending on how one defines the motor and a no load condition.

What you're looking for is the magnetizing current, which is constant, added to the losses in efficiency of circuit design....Typically the magnetizing current will be between 20-30% of full load current.....So probably around 20 amps.....give or take...

http://forum.allaboutcircuits.com/threads/load-current-and-no-load-current-in-ac-induction-motors.72544/

The term "no load" is hard to define consistently. For instance, on an unloaded conveyor, there is still considerable friction, and "no-load" current might be even 60% of full-load current. On the other hand, if a motor is completely disconnected from external loads, internal friction and windage can still make "no-load" current around 30% of full-load. Your best bet is to measure actual current under your own defined conditions.

Why do you want to know? No-load current on an AC induction motor is almost completely useless information other than in comparative analysis of empirical data from measurements, meaning something like "It was 30A last month when the voltage was 400V, it is 31.2A this month when the voltage is 400V, ergo something is wrong." another might be the detection of a broken belt, but technically, that is monitoring of PARTIAL load current, in that if the current drops BELOW that previously measured level at which the belt is connected, the belt must have broken. Other than that, trying to ca Culate unloaded current is a waste of time, or a homework question from a professor who wants to see how many of his students are incapable of thinking about a situation fully.

Now, your highly descriptive thread title was plural, but you have as yet only posed one question. Where are the rest of them?

I agree that the no-load current is a completely useless piece of information from a design perspective. It can be a very insightful bit of information for understanding how an electric motor actually works.

I suspect the OP has noticed that the current magnitude changes very little with a motor they can easily monitor while significantly changing the mechanical load without overloading this motor. This observation is what I believe leads to the no-load condition question. The OP probably cannot monitor the voltage vs current phase angle. This is where normal operational mechanical load changes will appear.

Both you (JRaef) and I can just as easily explain or baffle the OP why this is true. Without feedback from the OP we will never know which.

Sorry, it's not so useless, it can be very important, in Predictive maintenance, to evaluate any type of friction evolution from the system.

The current doesn't drop down as far as you might think. What happens is that the power factor changes so the current at no load is mainly inductive. Here is an example plot...

Induction motor

The NO LOAD current (i.e. - the motor is not energized any more) is always ZERO amps. If you happen to be referring to the minimal load required to spin the motor (+ whatever mechanical accouterments are attached), then that is always something that should be measured, not read off a nameplate. If you are speaking of unattached motor, then it could or should be on the nameplate.