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Thread: question for a leccie
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28th April 2008, 04:27 PM #1
question for a leccie
I am having problems with the power in my workshop.
I do not have power in the shop but use a Click 20 m/2400W max/10 amp heavy duty lead on a switched twin outlet reel connected to a 15 amp outletl. I always roll the complete lead out.
I connect my 1Hp/750W dust collector and my 1 Hp bandsaw to the outlets, switch them on and off, everything is fine. Sometimes, not all the time, when I switch them on again, it throws the safety switch. When I try to re-connect the safety switch it keeps on cutting out.
If I disconnect the machines, the cord still throws the safety switch when I flick the reel switch on.
I have put a multimeter on the cord and there is full connection through it on all 3 wires.
I connect my 1.5 hp airconditioner on the 15 amp outlet and have no problem.
I gather 750W = 1 hp, right?
That means I am drawing 2 hp or 1500W from the cord that is supposed to handle 2400 W/10 Amp and a 15 Amp outlet that is supposed to be able to handle around 4 Hp.
What is going on?
The only thing I can think of is that the switch on the reel is faulty?
TIA
WolffieEvery day is better than yesterday
Cheers
SAISAY
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28th April 2008, 04:47 PM #2
Not a leccie here, but it sounds like to me that the Safety Switch is getting warm with use and when it gets to a certain temp the current draw from starting the Bandsaw or D/C it keeps tripping it.
Cheers
DJ
ADMIN
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28th April 2008, 04:52 PM #3
even without the machines connected?
WolffieEvery day is better than yesterday
Cheers
SAISAY
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28th April 2008, 04:53 PM #4
Last edited by DJ’s Timber; 28th April 2008 at 04:55 PM. Reason: Add more info
Cheers
DJ
ADMIN
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28th April 2008, 04:57 PM #5
Had another thought, have you ever notice if the lead itself is getting warm or hot? It is a lot of current running through that lead to run the Dusty and Bandsaw. Dusties generally pull a lot of current.
Cheers
DJ
ADMIN
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28th April 2008, 05:03 PM #6
Actually haven't thought about that but, 20 metres is an awfully long cord, right?
WolffieEvery day is better than yesterday
Cheers
SAISAY
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28th April 2008, 05:56 PM #7
You may have to have look and see if you don't have some loose connections causing the heat.
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28th April 2008, 08:20 PM #8
Nar Nothing to do with heat at all
IMO you have a faulty lead.
Safety switches trip(turn off) on earth Leakage.
In layman's terms
The safety switch looks at electricity (Current in this case)going out and compares it to what is coming back.
If there is a big difference the thing switches off.
In your case the electricity is leaking to the earth conductor from the active or neutral conductors (Or both)
In other words the insulation is breaking down
If you know a friendly sparkie he will be able to prove this with with his insulation resistance tester.
Of course If there is no load (Current flowing) the safety switch will not see a problem remember they work on current flow.
It may not happen all the time because of the way the lead is rolled out or the amount of current flowing.Electricity:
One Flash and you're ASH
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28th April 2008, 09:13 PM #9Code:
Safety switches trip(turn off) on earth Leakage. In layman's terms The safety switch looks at electricity (Current in this case)going out and compares it to what is coming back. If there is a big difference the thing switches off.
That is what I thought too.
I had a suspicion there was a break inside the lead, which would not show all the time but, when we shifted the lead around, say changing from one machine to another, the inside would move, particularly if the breakage is around the plug, or if the fault was in the switch, right?
And that's why the multimeter would not show a fault when sitting on the continuity mark, I am only measuring one wire at a time.
Going out to buy a new lead tomorrow
WolffieEvery day is better than yesterday
Cheers
SAISAY
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28th April 2008, 11:12 PM #10
Member
- Join Date
- Dec 2007
- Location
- Adelaide
- Posts
- 7
A safety switch detects the difference or imbalance in current draw between the active and neutral conductors, when the current draw varies by more than a small preset value (about 30Ma I think) the safety switch trips and disconnects the power. If you accidently touch either the active or neutral then an imbalance will occur and trip the rdc saving you from possible electrocution. An imbalance in current draw between the active and neutral wires can exist in a situation where an extension lead is plugged in and left out in the open and damp grass/weeds cause a small current flow from the active or neutral to ground tripping the rcd even though there is no equipment connected to the extension lead. Like nev says its probably your lead and most likely to be at the twin outlet end where possibly sawdust has got into the socket.
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29th April 2008, 10:30 AM #11
It looks like I found the culprit by a process of elimination.
It is the bandsaw.
As soon as I plug it in and without turning the power point on (ie no actual power on the machine) it triggers the safety switch.
Strange though, that cord has never been squashed or anything, could it be the actual magnetic switch on the machine?
Bummer, the machine is only 6 months old and I live in the sticks where it takes weeks just to get a leccie to come and have a look
WolffieEvery day is better than yesterday
Cheers
SAISAY
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29th April 2008, 10:50 AM #12
Sounds like a similar prob that someone else had, it was a build up of sawdust in either the motor or the switch. If you've got a compressor try blowing out the motor and switch with compressed air.
Cheers
DJ
ADMIN
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29th April 2008, 01:34 PM #13
We did and it seems to be working now.
What I found when I took the covers off the machine was 2 bung holes from the wheel cavity into the power column and about 15 mm of dust on top of the connections.
Blew all the dust out and plugged up the holes.
Fingers crossed that it will keep on working.
WolffieEvery day is better than yesterday
Cheers
SAISAY
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29th April 2008, 01:39 PM #14
GOLD MEMBER
- Join Date
- Aug 2007
- Location
- Brisbane
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- 0
Tried that with mine, and it still isn't working. For me it looks like a trip to the repairer or a new motor off ebay. Actually, may not be a bad time to upgrade the motor power. Not much point having 6 inch high throat when the motor stalls cutting more than about 2" Good luck with yours Wolffie
PeterThe other day I described to my daughter how to find something in the garage by saying "It's right near my big saw". A few minutes later she came back to ask: "Do you mean the black one, the green one, or the blue one?".
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30th April 2008, 02:03 AM #15
Electrician
- Join Date
- Sep 2007
- Location
- Thailand
- Age
- 63
- Posts
- 90
After you've experienced problems like these, it's a good idea to perform an insulation resistance test on the motor (& the extension lead while your at it). If foreign matter inside a motor has been causing earth leakage current, it's also likely that some debilitation of the winding insulation may have occurred.
For a single phase motor, no greater than 500v should be used in an insulation resistance test. If the results of the test show less than about 10 Megohms, you may have ensuing problems. If the results are close to 1 Megohm or less, the tested device is dangerous & needs to be repaired or replaced.“I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success... Such emotions make a man forget food, sleep, friends, love, everything.” - Nikola Tesla.
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