Fuse Blowing on small motor

[infinity]

have been asked us to look at installing a different fuse as the 13A plug top keeps blowing when they try to start the Motor, its a very small bench compressor.

He seems to think it requires a fuse to allow the inrush of current, but the plate of the motor states its only 1500W so should this be blowing a 13A fuse on start up?

I cant see why it cant be hard wired in to a circuit with a 10A type C MCB instead?

 

[micknew]

Was it supplied with a plug top on it?
The starting current would exceed 13A.

 

[micknew]

Protect it with a 10A type C as you suggest.

 

[infinity]

I'm not sure if it was supplied with it or they put it on.
Yes that's my thinking, a small 2 way DB for the motor,

Thanks

 

[Besoeker]

Was it supplied with a plug top on it?
The starting current would exceed 13A.

I don't know what it is for single phase motors - I rarely deal with them - but for a three phase machine it would be typically be six times full load current or greater. We are given power (1500W) but not power factor or efficiency. So even running current could be close to 10A. Maybe the OP can shed some light on that.

In short, it doesn't surprise me that a 13A fuse blows.

 

[micknew]

Running current would be 8.05A assuming 230V, 90% eff, and 0.9 pf.
So 10A type C ok.

 

[davesparks]

That data plate looks like the plate from the compressor unit, not the plate from the motor.
I read that as being a compressor which requires a motor which can deliver 1.5KW of mechanical power.
Have a look at the data plate on the motor and see what that has to say.

 

[micknew]

That data plate looks like the plate from the compressor unit, not the plate from the motor.
I read that as being a compressor which requires a motor which can deliver 1.5KW of mechanical power.
Have a look at the data plate on the motor and see what that has to say.

The rating plate says 50Hz, must be referring to the motor rating.
The plate also gives compressor data.

 

[davesparks]

The rating plate says 50Hz, must be referring to the motor rating.
The plate also gives compressor data.

But no voltage, power factor, number of phases, number of poles, efficiency

 

[micknew]

But no voltage, power factor, number of phases, number of poles, efficiency

Never seen no. of poles on a rating plate and I said assuming 0.9 eff. and 0.9 pf.
I guessed it was single phase 230V because it had a plug top on it lol.

 

[davesparks]

Never seen no. of poles on a rating plate and I said assuming 0.9 eff. and 0.9 pf.
I guessed it was single phase 230V because it had a plug top on it lol.

Assumptions and guesses!

 

[micknew]

Assumptions and guesses!

No guesses but assumptions (which give a fairly accurate answer) based on experience.
Its what they teach you at college.

 

[netblindpaul]

I would not say that it is off a compressor, in fact I can almost be sure it is not a compressor.

Why are you all trying to apply BS7671 theories to machinery which is not covered by BS7671?

Again.

 

[davesparks]

I would not say that it is off a compressor, in fact I can almost be sure it is not a compressor.

Why are you all trying to apply BS7671 theories to machinery which is not covered by BS7671?

Again.

Is it a vacuum pump? I can't make sense of it having a vacuum rating otherwise

 

[micknew]

Infinity, your bench compressor will comfortably/safely run off a 10A Type C circuit breaker.
If it 'morphs' into a vacuum pump it will still be OK.
God help us.