Flaky electrical supply to workshop. Options?

[Roger440]

In the abscense of a garage at the moment, im renting a workshop at the local farm. 

 

Sadly, it seems the incoming electrical supply isnt up to much.

 

Most stuff is OK, but the compressor is an issue. Basically, it struggles to start. The colder it is, the worse it gets, no doubt due to drag increasing on the motor.

 

Clearly the right answer is to upgrade the incoming power supply. But not my farm or my building.

 

Given the problem is only on start up, and just before it trips out at peak pressure, i only need short periods of extra incoming.

 

Ive tried to find a solution, but not sure im using the right terms. Are the products avalable, such as a battery bank etc, that will, effectively support those peak loads?

 

Im not sure im explaining it well, but hopefully the brighter minds than mine here might have some ideas?

 

Im keen to avoid a generator as this is way to much messing about, though clearly, its an option.

 

Thoughts?

[Onoff]

  On 24/11/2020 at 19:17, Roger440 said:

Sadly, it seems the incoming electrical supply isnt up to much.

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Worth checking all the terminals are tight for a start if you can do that safely.

 

As likely suffering from volt drop

 

Do you know the cable run length in metres and what size the cable is? If it's armoured cable look for something like the 4x2.5 below. G'teed it won't be white anymore! ? Often it's raised / embossed.

 

[Timedout]

The compressor starting current is too high for the supply circuit breaker. Perhaps the compressor has something wrong with it or it’s just too big. Easiest solution is to ditch it and get one that has an engine if you really need a big one or get a smaller one. If I recall the issues when I had one, the direct drive compressors have a lower volume delivery but higher starting current than the belt drive compressors. 
My twin cylinder direct drive compressor would stall my generator if the engine was not fully warmed up. My planer thicknesses did the same. Both had 2.2kW induction motors. The generator could run them well within its parameters but the starting current was a problem.

 

You could look at the supply. circuit breakers come in different types  denoted by a letter, B or C . Some sustain a higher current for longer before tripping. Look to see what’s there and get advice from an electrician. May be a cheap swap of a circuit breaker.

 

 

 

 

Edited November 24, 2020 by Timedout

[Onoff]

  On 24/11/2020 at 19:52, Timedout said:

The compressor starting current is too high for the supply circuit breaker. Perhaps the generator has something wrong with it or it’s just too big. Easiest solution is to ditch it and get one that has an engine if you really need a big one or get a smaller one. If I recall the issues when I had one, the direct drive compressors have a lower volume delivery but higher starting current than the belt drive compressors. 
My twin cylinder direct drive compressor would stall my generator if the engine was not fully warmed up. My planer thicknesses did the same. Both had 2.2kW induction motors. The generator could run them well within its parameters but the starting current was a problem.

 

You could look at the supply. circuit breakers come in different types  denoted by a letter, B or C . Some sustain a higher current for longer before tripping. Look to see what’s there and get advice from an electrician. May be a cheap swap of a circuit breaker.

 

 

 

 

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Did you read the op? He HASN'T got a generator.

[Roger440]

  On 24/11/2020 at 19:46, Onoff said:

 

Worth checking all the terminals are tight for a start if you can do that safely.

 

As likely suffering from volt drop

 

Do you know the cable run length in metres and what size the cable is? If it's armoured cable look for something like the 4x2.5 below. G'teed it won't be white anymore! ? Often it's raised / embossed.

 

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Terminals all checked. Done that

 

Im not seeing a volt drop with a meter plugged in to the socket thats its plugged in to. But i do see a rapid climb in current consumption when its about to cut out.

 

Supply comes from the other half of the building. Its the incoming to that that i think is the issue. A small bit sticks out of the ground. Ive got 16mm armoured under my drive. Its WAY bigger than that. But thats not to say its that size all the way. Difficult to know. Not my farm

[Timedout]

Yes transposed a word there. Thanks for your rude comment though.

 

 

 

 

[Roger440]

  On 24/11/2020 at 19:52, Timedout said:

The compressor starting current is too high for the supply circuit breaker. Perhaps the generator has something wrong with it or it’s just too big. Easiest solution is to ditch it and get one that has an engine if you really need a big one or get a smaller one. If I recall the issues when I had one, the direct drive compressors have a lower volume delivery but higher starting current than the belt drive compressors. 
My twin cylinder direct drive compressor would stall my generator if the engine was not fully warmed up. My planer thicknesses did the same. Both had 2.2kW induction motors. The generator could run them well within its parameters but the starting current was a problem.

 

You could look at the supply. circuit breakers come in different types  denoted by a letter, B or C . Some sustain a higher current for longer before tripping. Look to see what’s there and get advice from an electrician. May be a cheap swap of a circuit breaker.

 

 

 

 

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I should probably clarify. The breaker doesnt trip. The motor pulses, and after 5-15 seconds, the compressor trip operates. Leave it a minute or 2 and you can have another go. Usually with the same result.

 

Its a hydrovane compressor. It works fine at work. The farmer also confirmed his compressor used to do the same occasionally when it was in the same building (well the other side of the wall.)

[ProDave]

Can you clarify WHAT is "tripping out"?

 

Farm electrics are legendary, and not usually in a good way.

[PeterW]

  On 24/11/2020 at 21:13, ProDave said:

Can you clarify WHAT is "tripping out"?

 

Farm electrics are legendary, and not usually in a good way.

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Nothing wrong with short bits of 6” nails as fuses ......

[Onoff]

I once helped a smallholder who's wood work shed 230V supply would trip the house RCD every time he plugged it in. The supply was a red, 5-pin Commando socket on the house wall. Supply to the shed was 3-core, rubber flex that ran across the yard, on the surface...under the wood pile.

 

I stuck the Megger on the lead and the IR was way down. 

 

Cleared some logs and found a cut mark in the lead. 

 

"That'll be Dad with the axe!"

 

I watched incredulously as he proceeded to spray Damp Start on the damage. Was even more impressed the IR went up.

 

Walk away! 

[ProDave]

My "best" farm one was main house rcd tripping.  Traced it to a caravan lead plugged into a socket, out of the window across a yard. Half way across it joined to a second caravan lead eventually to the caravan that some farm hand was living in.

 

The joint between the 2 leads was underwater in a puddle.

[Onoff]

Soaking wet, rat chewed cable in a ceiling. Could actually hear it fizzing for a bit before the 30A breaker tripped. RCD just didn't work period.

 

Mole grips attaching an earth wire to a scaffold pole in the ground. TT farm style! 

 

Live corrugated tin roof was a good one. 

 

 

[Roger440]

  On 24/11/2020 at 21:13, ProDave said:

Can you clarify WHAT is "tripping out"?

 

Farm electrics are legendary, and not usually in a good way.

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The compressor itself trips out. I assume some king of ovrload or thermal trip.

[Onoff]

  On 24/11/2020 at 20:03, Timedout said:

Yes transposed a word there. Thanks for your rude comment though.

 

 

 

 

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Apologies, weird day. No excuse, I know!

[ProDave]

  On 24/11/2020 at 21:44, Roger440 said:

 

The compressor itself trips out. I assume some king of ovrload or thermal trip.

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Then if you are not seeing any voltage drop either it's a compressor issue.

 

Is the cut off pressure set too high?  Is the oil in the compressor okay?

[Onoff]

Actually my little compressor sometimes struggled to start when new and needed a whack... occasionally it'd trip on the overload. Something stuck / tight probably. Got better the more it was used. 

[Onoff]

Silly question but is it a little compressor with a short duty cycle i.e getting hot if running for too long?

[dpmiller]

Is the oil fresh, and might you try replacing the start/ run capacitors?

[Roger440]

  On 24/11/2020 at 21:45, ProDave said:

Then if you are not seeing any voltage drop either it's a compressor issue.

 

Is the cut off pressure set too high?  Is the oil in the compressor okay?

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Its 150psi, which is what its supposed to be. It worked fine in the previous workshop. Thats not to say its not developed a faul of course.

[Roger440]

  On 24/11/2020 at 22:35, dpmiller said:

Is the oil fresh, and might you try replacing the start/ run capacitors?

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Oil about a year old. But barely been used until recently.

 

I dont really understand what effect the caps have, or how i can know if they need replacing?

[Roger440]

  On 24/11/2020 at 21:59, Onoff said:

Silly question but is it a little compressor with a short duty cycle i.e getting hot if running for too long?

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Its main issue it wont start from cold. Once its nice and hot, its fine. But it doesnt really run long enough to get properly hot.

[Temp]

  On 24/11/2020 at 20:01, Roger440 said:

Im not seeing a volt drop with a meter plugged in to the socket thats its plugged in to.

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Thats a bit odd. 

 

Is the voltage lower at the farm compared to at work? 

 

[dpmiller]

  On 24/11/2020 at 22:46, Roger440 said:

 

Oil about a year old. But barely been used until recently.

 

I dont really understand what effect the caps have, or how i can know if they need replacing?

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Capacitors slowly lose value with time and if the starting cap is low the motor will ramp up to speed more slowly whilst taking an excess of current, whereas the correct value will jolt the motor up to full speed (often using even more current !) so quickly that the overload trip doesn't have time to respond

 

eg whilst a 3Hp piston compressor will run off a 13A plug (running current between 11 and 14A generally) the starting current is somewhere around 40A for a second or two in my experience. If the capacitor has lost a bit of capacity- 20% say- it could be drawing 30A for five or more seconds...

 

Do you have a multimeter that has a capacitance range or an AC clamp meter? If not, just spend a tenner on a new capacitor...

[Roger440]

  On 25/11/2020 at 07:27, dpmiller said:

Capacitors slowly lose value with time and if the starting cap is low the motor will ramp up to speed more slowly whilst taking an excess of current, whereas the correct value will jolt the motor up to full speed (often using even more current !) so quickly that the overload trip doesn't have time to respond

 

eg whilst a 3Hp piston compressor will run off a 13A plug (running current between 11 and 14A generally) the starting current is somewhere around 40A for a second or two in my experience. If the capacitor has lost a bit of capacity- 20% say- it could be drawing 30A for five or more seconds...

 

Do you have a multimeter that has a capacitance range or an AC clamp meter? If not, just spend a tenner on a new capacitor...

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I borrowed a clamop meter. not conviunced on calibration, and it was very sensitive. But it showed 5 amps running, but when it started ti struggle, and then pulse it would rise to 15 amps

 

Interesting point about the cap.

 

After some suggestions elsewhere, getting it hot first made all the difference. I ran it offlosad for an hour, and then reconnected. It was fine from that point on, until it didnt run for an hour or so, then it was back to tripping out. Ive also discovered putting a sump heater on the compressor is a done thing.

 

All that sais, after using air most of yesterday, ive concluded that it isnt really big enough. For a 3hp compressor, air output is poor compared to my old piston compressor. Im going to last that in and see how that performs. Other than very noisey!!!

[dpmiller]

sadly screws are smaller than pistons for a given HP (at our levels anyway) . Best option I've seen (but not yet tried) is this:

 

https://www.fps-compressors.co.uk/phazair-230_5_510-270-vsd_variable_speed_receiver_mounted.html

 

on-board phase converter/ variable speed drive.