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Topic Title: Emergency stop/start switch tripping
Topic Summary: I'm not sure I trust the advice give
Created On: 09 April 2015 06:57 PM
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 09 April 2015 06:57 PM
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Zs

Posts: 3814
Joined: 20 July 2006

L.O.

For 'give' read 'given'...I must replace this keyboar .. It got tea down it.

Officially, I'm on holiday right now, building a shed.

But.

Old Doctor H has called about his ageing swimming pool installation and has told me what he is expecting me to do. He does that, but I enjoy traditional English Eccentrics so I let him get away with it. He does my head in but I quite like him at the same time. He has stories to tell and once got stabbed by a patient, that kind of thing...when I have the time.

Imagine a pristine outdoor pool, crystal clear, with pump and all that in an outhouse. Now imagine it with an old and tired electrical installation with loads of sangamo timers and all sorts. I condemned it about two years ago, in writing, and excluded it from full inspection. Notified his insurer. I advised a pool specialist be called to address it.

The pool company instructed a new pump/cleaner/filter thing.. The big thing that you can use to back-pump, filter, run a kreepy krauly and all that. He has a new one.

It has an emergency stop button on it (from the last one, not new) which is one of those with the big red button and a smaller green button.

The new pump thing trips that emergency stop. He says..

He has decided that I am to bypass it () He tells me that it was originally installed for the heater/boiler which is no longer used.

Incidentally, Dr H is about 93 and still swims every day. No heating and really, he does it every day from his Zimmer frame. Quite a sight to behold.

I do not think that those switches have any overcurrent protection. I do not think that they serve any purpose other than 3mm contact gap and switching off and switching on. The Pool has an enforced (by me) 30mA RCBO at the upstream end from the house DB which was working three months ago and is holding well.

I have agreed to go over at the end of next week, with another electrician, and have a look/get some readings.

Am I right that the emergency stop buttons serve no purpose other than cut-out and should not be pinging into the open position?

Dreading it.. he talks but doesn't listen or hear and I want to keep him safe.

What do you reckon? Dodgy switch or something deeper? I've not heard of an emergency cut out going soft before so I hesitate to take that route of thinking. Any experience with a dodgy spring or anything in these devices?

No urgency. This is the end of next week and I love it that he has an RCBO.

Thank you.

Zs
 09 April 2015 07:21 PM
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jj4091

Posts: 57
Joined: 20 July 2007

Emergency stop switches are available in NVR (no volt release) & overload protected versions so you would need to know which make it was. Or are you saying you think the one installed is NVR?
 09 April 2015 07:37 PM
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iomtt

Posts: 54
Joined: 30 April 2008

Could be a thermal overload going,

Any photo available
 09 April 2015 07:55 PM
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HarryJMacdonald

Posts: 409
Joined: 15 May 2002

I would have thought that the filter has some sort of control circuit with various bits of logic. Possibly electronic but may all be mechanical.

I would expect the EM stop to be part of that circuit. The Em stop should trip the pump not the other way round. Faulty motor overload setting or faulty logic in the controller seems more likely.
 09 April 2015 08:14 PM
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primo

Posts: 517
Joined: 10 January 2008

Sounds like it's a DOL starter, possibly with the overload set too low for the new pump?
 09 April 2015 08:18 PM
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mapj1

Posts: 9371
Joined: 22 July 2004

If the EM switch is simply re-purposed from the ancient one, that used to control a smaller load , if it incorporates overload protection, it is quite likely to have a slightly in-appropriate trip coil.
often these are like a self latching relay - where the 'go button' is momentary , and then once contacts close in parallel with the button, so the button can be released. Any fault in the stop loop breaks the supply to the holding coil, and then it cant re-start without pushing the go button again.

Actually there are many options - it may have a slow acting thermal part affected by the ambient temperature, or there may be a low voltage release that lets go too soon if it is a 400V coil on 230V, or a series coil that requires a minimum load current to hold in. I suggest going along and photograph the innards, and maybe someone will recognize it, or just seeing if by adding extra load you can make it more or less stable.
If the new equipment does not need the emergency stop, then the advice to jump it out may not be so foolish - an ordinary switch would likely be enough.

see relay coil and contacts K1 in this example A lathe control with a shunted start button and many interlocks in a break loop

-------------------------
regards Mike


Edited: 09 April 2015 at 08:26 PM by mapj1
 09 April 2015 09:13 PM
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Zs

Posts: 3814
Joined: 20 July 2006

Thank you so much. I've not been aware of these ones with anything but contact break so I'm glad I asked you.

Friday 17th I will get you a photo of the outards and innards, insert as an avatar and ask you again. I'll also get some stop-start current measurements and anything I can. Yes, it might have been re-appropriated because Dr H seems to think it was the switch for the old heater for the pool ( via the household oil boiler) which they no longer use. It is so old in there that any new cables or moved dust on switch covers will tell a story.

Back next week with more, thank you.

Zs
 09 April 2015 10:51 PM
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paulskyrme

Posts: 1285
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Originally posted by: jj4091

Emergency stop switches are available in NVR (no volt release) & overload protected versions so you would need to know which make it was. Or are you saying you think the one installed is NVR?


No they are not.
An emergency stop device must meet stringent EN standards, and they have no, no volt release nor overload protection within them.
End of.
They are emergency stops to the EN standard and nothing else.
Any overload protection or NVR are to different EN standards.
End of.
 09 April 2015 10:53 PM
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paulskyrme

Posts: 1285
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Zs,
If you want machinery circuits guidance which complies with the machinery directive, the LV directive and EN 60204 etc. you know where to get me, a lot of the above is not relevant if the "machinery" is "machinery" IYKWIM, you can forget 7671.
 09 April 2015 10:58 PM
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paulskyrme

Posts: 1285
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Unusually, I have to say that the circuit given by Mapj1 is not really acceptable these days.
Things have moved on somewhat.
Give me a shout if you want the real detail.
I won't post it on here, as in the past I have been ridiculed for posting data which is exactly correct to the EU directives and EN standards, but, the posters on here did not like it, so, now I won't any longer post the exactly correct information, because people don't like to realise that they are wrong when they design machinery circuits.
 09 April 2015 11:55 PM
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alancapon

Posts: 6882
Joined: 27 December 2005

I must admit that the unit described by Zs sounds like a DoL starter rather than an emergency stop arrangement. It is likely that if you remove the cover of the unit, there will be a motor overload inside, which is set a bit enthusiastically for the new motor.

Regards,

Alan.
 10 April 2015 08:38 AM
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AJJewsbury

Posts: 15849
Joined: 13 August 2003

No they are not.
An emergency stop device must meet stringent EN standards, and they have no, no volt release nor overload protection within them.
End of.
They are emergency stops to the EN standard and nothing else.
Any overload protection or NVR are to different EN standards.
End of.

But that might not necessarily be the case when looking at something left over from a decades old existing installation?
- Andy.
 10 April 2015 10:17 AM
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Ricicle

Posts: 894
Joined: 23 October 2006

In it's simplest form, pool electrical equipment will consist of a filtration pump (or pumps), dosing equipment (if automatic) and heating (if electric) In the absence of advanced controls there is usually only a DOL starter for the circulation pumps. Is it possible it is (or similar to) those MEM types where the green start button is flush but the red stop button is mushroomed so can function as an emergency stop or functional stop?
As above it just sounds like the overload is set incorrectly. Other factors maybe a tired contactor or loose connection?
Or is the starter wired correctly for a single phase motor (assuming the pump is single phase)?

-------------------------
Empty barrels make the most noise.
 10 April 2015 01:32 PM
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Dave69

Posts: 612
Joined: 16 July 2011

How often does the starter "stop"? once an hour, day, week,,,,,,,,,,,,

Are you sure the stop and start buttons are even wired in now? as you say he now has a new pump etc. installed, surely who ever installed that would not of used the old starter.

Stop buttons are wire "fail safe" in that in a healthy condition they are always closed and either holding the supply onto the emergency stop relay circuit or directly onto the contactor coil, in the latter any overload contact or other safety device will be wired in series. If the contactor is dropping out it will therefore either be a lose wire, a overload unit opening or some other safety device operating.

Check the operating current and make sure the overload is set correctly.
 10 April 2015 04:48 PM
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Zs

Posts: 3814
Joined: 20 July 2006

Brace yourselves...I have found a photo of the installation as it was when I specifically refused to test it and then to leave until it was RCD protected from its origin. I've not seen it since then but I've a feeling it is going to be the same when I go there next Friday.

So sorry if this messes with the layout of the thread, I know that photos sometimes do. But you'll like it.

The switch in question, I think, is the one on the bottom right.

Ready? I'm about to attempt to post a photo. Welcome to my world!

Edit..failed in spades at posting a pic direct so there it is in the avatar. You'll have to zoom your screen...press ctrl and wiggle the mouse wheel.

Zs

Edited: 10 April 2015 at 05:04 PM by Zs
 10 April 2015 05:17 PM
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iomtt

Posts: 54
Joined: 30 April 2008

Behind the cover of that unit is a thermal,overload at the bottom which are interchangeable
Clamp meter the load, check the data plate on the motor and adjust the amperage lever or change the overload to suit the running current not the start up current


Assuming the worst case scenario
If that doesn't work check the motor windings,

Also from the photo it looks like single phase, but if it is 3 phase check u have all three phases and not running on 2

Hope that helps

Looks like a Brooke Crompton unit to me
 10 April 2015 05:20 PM
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iomtt

Posts: 54
Joined: 30 April 2008

Or possibly a IMO Unit
 10 April 2015 08:54 PM
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mapj1

Posts: 9371
Joined: 22 July 2004

I think strictly that pic is not what Paul or the EN standards understand as an E-Stop; but equally may not be protecting equipment that strictly requires an E-Stop, but yes it is a way of stopping it - emergency or not ;-)

(grins sheepishly , I stand corrected- yes actually I do know about having dual loops and force guided second contacts and so forth - but its been a while and I'm happy to be shown to be getting dated - none the less I was describing what I expect in a simple on -off box and there are plenty of "legacy" installations out there, especially in private hands, and even some new ones that are not to the letter of the standards, that probably really should be E-stops)

It is however a box with an on and off momentary push button and an interlock - albeit quite a new one ;-) and I'll wager something quite like a motor overload trip lurks in there - similar in function if not form to
http://www.tlc-direct.co.uk/Te...MEM_Starter.pdf


- in which case convince yourself the motor is not overloaded before opening it up a bit.
Does it trip for example when switching to back wash, or just after a few minutes running, or instantly.

Let us know how it goes.

@Zs Email me the larger pic if you want me to put it on a webhost so it can be linked to here.

-------------------------
regards Mike
 10 April 2015 09:28 PM
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HarryJMacdonald

Posts: 409
Joined: 15 May 2002

From the photo it looks like there is only one cable to the box. If there are 2 then I agree with the above, if only one then the overload is probably in whatever box the other end of the cable goes to.
 10 April 2015 09:49 PM
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iomtt

Posts: 54
Joined: 30 April 2008

I would recommend any motor over 1 amp be protected via overload and simply follow the steps I posted earlier to work out what the problem could be
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