http://www.electriciansforums.co.uk/ Discussions on Three Phase, Motors, Trunking, electronics and other industrial electrics en Tue, 07 Sep 2010 17:34:55 GMT vBulletin 60 http://www.electriciansforums.co.uk/images/misc/rss.png http://www.electriciansforums.co.uk/ http://www.electriciansforums.co.uk/commercial-industrial-electrical/21862-coming-off-3-phase-supply.html Mon, 06 Sep 2010 17:14:35 GMT I have been asked to carry out a job and would like to know if anyone can see any problems with what I intend to do 3 phase and neutral car lift... I have been asked to carry out a job and would like to know if anyone can see any problems with what I intend to do

3 phase and neutral car lift supplied via 2.5 mm cable protected by 3 phase 20amp mcb I intend to come off 1 phase to supply a 13amp rcd protected twin socket to supply drills hand lamps etc

do any electricians see in problems in doing this I am an Niceic approved contractor and am stuck on this one ]]> Commercial and Industrial Electrical Burton1979 http://www.electriciansforums.co.uk/commercial-industrial-electrical/21862-coming-off-3-phase-supply.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21793-3-phase-help-required.html Sun, 05 Sep 2010 10:46:56 GMT LADS I HAVE BEEN ASKED TO BRING A 3 PHASE SUPPLY FROM THE MAIN BOARD TO A LOCATION THAT WILL HAVE A COLD ROOM. I DON;T YET KNOW HOW MANY AMPS WILL BE... LADS I HAVE BEEN ASKED TO BRING A 3 PHASE SUPPLY FROM THE MAIN BOARD TO A LOCATION THAT WILL HAVE A COLD ROOM. I DON;T YET KNOW HOW MANY AMPS WILL BE REQUIRED BUT I JUST NEED HELP WITH THE EQUIPMENT NEEDED. DO I NEED TO FIT A 3 PHASE BOARD NEAR THE COLD ROOM. IF U LIVE NEAR WEST LONDON MAYBE YOU CAN DO A FEW DAYS WORK AND I CAN LEARN FROM U. IF U ARE UP 4 A FEW DAYS WORK PRIVATE MAIL PLEASE:cool:. TANX IN ADVANCE ]]> Commercial and Industrial Electrical m25maintenance http://www.electriciansforums.co.uk/commercial-industrial-electrical/21793-3-phase-help-required.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21745-job-interview-skill-test.html Fri, 03 Sep 2010 20:41:26 GMT ive got a second interview coming up for a large food manufacturing company which includes a skill test, any maintenance electricians here that have... ive got a second interview coming up for a large food manufacturing company which includes a skill test, any maintenance electricians here that have done one and what did it involve? or maybe your company sets them for new prospective employees? ]]> Commercial and Industrial Electrical pmac10 http://www.electriciansforums.co.uk/commercial-industrial-electrical/21745-job-interview-skill-test.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21673-voltage-sensative-eqipment-disaster.html Thu, 02 Sep 2010 06:42:10 GMT Hi, i am an Electrical contractor but also carry out Mechanical works. On this particular project we were only carrying out the Mechanical... Hi,
i am an Electrical contractor but also carry out Mechanical works. On this particular project we were only carrying out the Mechanical installation. This was a boiler house replacement that consisted of a mechanical control panel and BMS system. The control panel was manufactured by a sub contractor and they also carried out the field wiring and supplied all the sensors and controls. The testing and commissioning was completed on all the equipment on a temporary supply. However, when the electrical contractor put his 3 phase supply to the mech panel it blew all the controls, including the field controls.

Does anything spring to mind as to how this may have been caused? It is as if there was transiant voltage but i cant see how this may have been caused?

The blame is with somebody but the electrical contractor will not accept it is him as he says he only put the supply to the panel. However, the controls sub contractor did put type D mcbs in. Would this have caused the circuits not to trip out under fault conditions?

Any input would be much appriciated.
Thanks ]]> Commercial and Industrial Electrical liamraffo http://www.electriciansforums.co.uk/commercial-industrial-electrical/21673-voltage-sensative-eqipment-disaster.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21598-step-down-transformer.html Tue, 31 Aug 2010 10:07:04 GMT Hi, I recently bought two motorized Dremel 6000 contour sanders from USA. The operating power stated on the sander is 120V 50-60Hz 1.15A I... Hi,

I recently bought two motorized Dremel 6000 contour sanders from USA.
The operating power stated on the sander is 120V 50-60Hz 1.15A

I live in Malaysia. The household power rating is 240V 50Hz up to a max of 13A.
I used a new 500W step down transformer to power the sander.

The step down transformer steps 240V down to 120V. It is an auto-transformer, with only one winding.
The transformer output shows 120V when measured on a multimeter.

The 1st sander operated for about an hour before it failed. I did not operate it continuously for the entire hour but rather few minutes each time. I disassembled and assembled the sander and it operated again but not for long before it failed again just after a few minutes. I disassembled the sander and checked the resistance of every coil and found out that one of the coils is open. There is no way it will operate until the coil is rewind.

The 2nd sander operated only for a few minutes before it failed. I dismantled the sander and checked the resistance of every coil and all look good.

The sanders is built in with an adjustable speed controller. The input power is connected to the controller before it reaches the coils.

Can an auto-transformer cause this problem?
Can a difference in frequency (50 vs 60) cause this problem?

Thanks for looking. :)

Cheers
Marcus ]]> Commercial and Industrial Electrical marcus9x9 http://www.electriciansforums.co.uk/commercial-industrial-electrical/21598-step-down-transformer.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21588-how-calculate-sizing-vacuum-circuit-breaker.html Tue, 31 Aug 2010 02:30:03 GMT Hi- I am looking for some help/ advice please. I'm confused about how How to calculate sizing of vacuum circuit breaker.

This project I work on it use 40m0A TP Vacuum circuit breaker to support pump 800 kW 11kV

I calculate the current just 49.4 A (800*1000/1.732/11000/0.85 ) I don't know why it use 400 A Someone know please explain me

Sorry for bad english i'm not native language



]]> Commercial and Industrial Electrical mooyong http://www.electriciansforums.co.uk/commercial-industrial-electrical/21588-how-calculate-sizing-vacuum-circuit-breaker.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21516-disabling-fire-alarm-zones.html Sun, 29 Aug 2010 11:03:34 GMT I work in a reasonably sized food factory split into 10 zones.We have from time to time the need to disable certain zones be it for clean downs or... I work in a reasonably sized food factory split into 10 zones.We have from time to time the need to disable certain zones be it for clean downs or when a fault occurs and the alarm company are callled.

I'm just curious as to the legality of disabling a zone as someone has asked the question is it legal to do so.

Thanks

Mike ]]> Commercial and Industrial Electrical mike3671 http://www.electriciansforums.co.uk/commercial-industrial-electrical/21516-disabling-fire-alarm-zones.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21429-ups.html Fri, 27 Aug 2010 16:41:44 GMT Anyone know about UPS systems? if so would you be able to point me in the direction of good source's of information.

Many Thanks ]]> Commercial and Industrial Electrical Flakey http://www.electriciansforums.co.uk/commercial-industrial-electrical/21429-ups.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21414-would-love-know-what.html Fri, 27 Aug 2010 06:44:42 GMT This photo’s got me fascinated would love to know what it is.



It’s in a government research station so no names, no pack drill. It looks like something Noah forgot to pack on to the ark (or arc).

All I can come up with is a 3 phase something or other :confused: ]]> Commercial and Industrial Electrical Tony http://www.electriciansforums.co.uk/commercial-industrial-electrical/21414-would-love-know-what.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21388-hot-plate-lamps.html Thu, 26 Aug 2010 14:54:33 GMT Any body with experience on them ?? got a restaurant wanting me to haver a look as part of a new maintenance contract i have got and before i go... Any body with experience on them ?? got a restaurant wanting me to haver a look as part of a new maintenance contract i have got and before i go there i wasnt to do a fact finding mission..!
;) ]]> Commercial and Industrial Electrical DurhamSparky http://www.electriciansforums.co.uk/commercial-industrial-electrical/21388-hot-plate-lamps.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21357-3-phase-labeling.html Wed, 25 Aug 2010 19:28:14 GMT hi all going to fit a 3pase board next week havent done any 3phase work for a bit can not rember what to lable up the tails should be as i will have... hi all going to fit a 3pase board next week havent done any 3phase work for a bit can not rember what to lable up the tails should be as i will have 3 browns going into the board from the metere wired in meter tails are they labled up l1 l2 l3 cannot rember any help would be great thanks ]]> Commercial and Industrial Electrical davetherave1979 http://www.electriciansforums.co.uk/commercial-industrial-electrical/21357-3-phase-labeling.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21259-milling-macine-problem.html Mon, 23 Aug 2010 19:03:03 GMT Hi all Had a phone call today asking if I would have a look at a milling machine that had been switched off last night and wouldnt power back up... Hi all

Had a phone call today asking if I would have a look at a milling machine that had been switched off last night and wouldnt power back up this morning.

Its a 3 phase machine with 3 main circits

1. motor
2. slurry pump
3. traverse

Checked power at isolater all fine
checked power in at transformer seems fine
checked out of transformer seems fine. The control gear is 24v

If the machine is powered on the tungsten filament light comes on.
None of the 3 starters for the above do anything. The emergency stop button seemed a bit dodgy so checked that out and it works ok.

If i push in the contactors manually and hold in place each part functions correctly. but there is no latching

I didnt have much time to look today so I said I would go back tomorrow to have a better look

any tips on this appreciated as the wiring diagram is lost, and I am still learning thanks ]]> Commercial and Industrial Electrical mrmatt http://www.electriciansforums.co.uk/commercial-industrial-electrical/21259-milling-macine-problem.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21206-vehicle-lift-stops-under-load-2-2kw-1ph-motor.html Sun, 22 Aug 2010 18:42:53 GMT Hi- I am looking for some help/ advice please.I am a mech fitter- not and electrician- all advice gratefully received- I have a 3 ton, 2 post lift.... Hi- I am looking for some help/ advice please.I am a mech fitter- not and electrician- all advice gratefully received-
I have a 3 ton, 2 post lift. It is electromechanical - screw type. No Hydraulics. It had a 3 phase motor fitted when I got it, but I only have 240V supply.

I have fitted a second hand Brook Crompton 2.2KW single phase 4 pole motor. Capacitor start/ Capacitor run.(The motor previously ran a pump)

Unloaded the lift works fine. When loaded with a 1200Kg car it will rise about 18" then stops. It will return to lowered position with no problem.

(The original 3phase motor was rated at 3KW, but the lift is available to buy new with a 2.2kw single phase motor. so the 2.2kw motor I fitted should be up to the job- I think. It is physically bigger/beefier than the 3ph motor that it replaced)

The lift is in good mechanical order and isn't binding or jamming under load
It is wired from a 30A supply with 6mm t/e

What can be the problem?

Thanks ]]> Commercial and Industrial Electrical Guinnal http://www.electriciansforums.co.uk/commercial-industrial-electrical/21206-vehicle-lift-stops-under-load-2-2kw-1ph-motor.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21203-capacitor-sizing-calculation.html Sun, 22 Aug 2010 18:00:36 GMT does anyone know how to calculate capacitor sizes for capacitor start, capacitor run single phase motor? manufacturer info not available. does anyone know how to calculate capacitor sizes for capacitor start, capacitor run single phase motor? manufacturer info not available. ]]> Commercial and Industrial Electrical devon1 http://www.electriciansforums.co.uk/commercial-industrial-electrical/21203-capacitor-sizing-calculation.html http://www.electriciansforums.co.uk/commercial-industrial-electrical/21186-question-about-non-automatic-transfer-switch.html Sun, 22 Aug 2010 16:06:19 GMT hi, i want to design non-automatic transfer switch by 2 contactors and push buttons. my question is do i need mechanical between the 2... hi,
i want to design non-automatic transfer switch by 2 contactors and push buttons.
my question is do i need mechanical between the 2 contactors? or it is enough to work with NO-NC for both contactors.
please help me ]]> Commercial and Industrial Electrical Sayedahmed http://www.electriciansforums.co.uk/commercial-industrial-electrical/21186-question-about-non-automatic-transfer-switch.html