Electricity consumption

[linga]

We have two vacuum pumps rated at 3.7kW
Say they run for four hours a day.
How many units will each one use ?
Are there circumstances when the motors may draw twice or three times the expected current( over a sustained period )?

 

[Netherfield]

Motors drawing two to three times their expected current would burn out quick time. Obviously they should have overload protection equipment fitted.

4 x 3.7 = 14.8 units

 

[linga]

Motors drawing two to three times their expected current would burn out quick time. Obviously they should have overload protection equipment fitted.

4 x 3.7 = 14.8 units

Isn’t that simplistic as it assumes 100% efficiency Also there is a figure on the plate of 20 odd amps so if that is the running current ( as opposed to starting current) then the consumption is more than 3.7 isn’t it ?

 

[Netherfield]

Isn’t that simplistic as it assumes 100% efficiency

Yes it's simplistic, there's all sort of variables like power factor correction to take in to account, Only way you'll get an exact reading is stick a meter on the circuit.

Assuming from your first post you think they are using far more than they should.

 

[pappuller]

Isn’t that simplistic as it assumes 100% efficiency Also there is a figure on the plate of 20 odd amps so if that is the running current ( as opposed to starting current) then the consumption is more than 3.7 isn’t it ?

You sure the motor isn't rated at 3.7 kw ?? Amps is different

 

[pappuller]

You sure the motor isn't rated at 3.7 kw ?? Amps is different

3.7kw will be approx 9amps on 3phase I think

 

[linga]

Motor is rated at 3.7 kw but on the plate it says amps 20

We have a wind turbine so we use our own electricity most of the time. However when the wind doesn’t blow we import electricity.
The problem we have is we are getting import spikes. Obviously the import will vary month to month depending on wind but what we are seeing is some spikes amount to three times what we think the maximum we could possibly use.
So we are trying to understand how that can happen

 

[Blue.]

3.7kw will be approx 9amps on 3phase I think

Two 5.5kw motors on mine are both 11amps.

 

[upnortheast]

As mentioned above best way to be sure is to get your sparky to connect a meter into the circuit. Be a 10 minute job. Leave it on each motor for a week then put it on `tother one
Sparky could do a spot check with a clamp meter for a rough guide.
The rating of the motor does not help with the calculation. The load will vary, it may only be running at 50% capacity - or 110%

 

[multi power]

Two 5.5kw motors on mine are both 11amps.

Are you sure? I make it 22 amps

 

[Blue.]

Are you sure? I make it 22 amps

Yes 11 each.

 

[multi power]

Yes 11 each.

Hang on, so 2x 5.5kw motors or 1 ?
5500 watts divided by 240 volts =22 amps

 

[Blue.]

Hang on, so 2x 5.5kw motors or 1 ?
5500 watts divided by 240 volts =22 amps

X2 5.5kw 3phase motors 11amps each

 

[multi power]

X2 5.5kw 3phase motors 11amps each

Ffs I didn't think of 3 phase

 

[linga]

As mentioned above best way to be sure is to get your sparky to connect a meter into the circuit. Be a 10 minute job. Leave it on each motor for a week then put it on `tother one
Sparky could do a spot check with a clamp meter for a rough guide.
The rating of the motor does not help with the calculation. The load will vary, it may only be running at 50% capacity - or 110%

I understand the load and hence electricity consumption will vary but what we are getting are import spikes up to three times the expected so for instance we have a maximum of around 50 kw of motor/water heater that could run and what we are seeing is an import rate (and for this I am assuming the turbine generates nothing which over a month does not happen) that equates to 150 kw ! Either that or the 50kw all runs three times as long as usual.
We are a dairy farm so consumption occurs at the same times each day and does not vary very much.
How can this be possible ?
The easiest answer I can come up with is someone has connected a load to the system without us knowing but this is not believable.

 

[TheRanger]

Is the turbine going backwards?

 

[vantage]

The easiest answer I can come up with is someone has connected a load to the system without us knowing but this is not believable.

Quite simple really. Your local itinerant has crocodile clipped your leccy supply for his cannabis factory!

 

[linga]

Quite simple really. Your local itinerant has crocodile clipped your leccy supply for his cannabis factory!

An impressive feat if they have because it would necessitate tunnelling into the site and about six inches down is good hard slate

 

[vantage]

An impressive feat if they have because it would necessitate tunnelling into the site and about six inches down is good hard slate

Indeed,but never say never!

 

[Blue.]

An impressive feat if they have because it would necessitate tunnelling into the site and about six inches down is good hard slate

Lads setting your turbine will have sold a connection to a neighbour.