push button stop/start single phase motor

[smashweld]

the auxillary block arrived, fits and works fine...the old three phase contactor was in a metal 'enclosure' that was earthed, the new contactor/overload/switches don't fit inside that so made another larger box for the new setup with alu, with the intention of just running an earth wire to it like the old setup, using glands for the cables to motor/mains... will that be sufficient? (will use proper wire colours for the final thing)

 

[Gareth J]

Sorry to tread hijack, but this seems like a good place to ask.

Looking for a decent waterproof stop/start box for this contactor

Any suggestions?

The original box is cracked/tatty anyway and the start button on the contactor is broken, so was hoping to replace the NO on switch and NC off switch with something in a waterproof enclosure that would hold the switches and contactor together....

Cheers

Edit;
For the cost of it, I should probably just get a complete new box;

Hylec DMS1-11D/S Automatic DOL Electric Motor Starter 5.5kW - Screwfix

Order online at Screwfix.com. Starting method for electric motors. Suitable for a number of applications including woodworking, dust collecting and metal recycling machinery. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

 

[Turbo]

It can be a problem getting a box to match an old contactor unit & that one looks like it has seen better days anyway.

As you say, it will cost very little more to buy a complete new box but you will need an overload that has the same amp range as your old one. Normal rule of thumb is to set the overload at max motor amps (on motor plate) plus 10%.

 

[Brad93]

Sorry to tread hijack, but this seems like a good place to ask.

Looking for a decent waterproof stop/start box for this contactor View attachment 392980

Any suggestions?

The original box is cracked/tatty anyway and the start button on the contactor is broken, so was hoping to replace the NO on switch and NC off switch with something in a waterproof enclosure that would hold the switches and contactor together....

Cheers

Edit;
For the cost of it, I should probably just get a complete new box;

Hylec DMS1-11D/S Automatic DOL Electric Motor Starter 5.5kW - Screwfix

Order online at Screwfix.com. Starting method for electric motors. Suitable for a number of applications including woodworking, dust collecting and metal recycling machinery. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

That;s a cheapy unit. Probably buy a new IP65 DOL starter of similar quality from amazon for £40

 

[Brad93]

https://www.amazon.co.uk/Magnetic-Electric-Starter-Control-Switch/dp/B0B4KDQL6Q/ref=sr_1_1_sspa?crid=3E2IEJ6GBXUAB&keywords=dol+starter&qid=1680763241&sprefix=dol+starter%2Caps%2C57&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1&smid=A3BGJVXOADZ30C

£45

Similar contactor to yours

 

[Brad93]

Double the money but its telemecanique so its good. https://www.tradesparky.com/circuit...ters-dol/schneider-le1d09n7-strtr-415v-5060hz

 

[Dave-sparks]

Normal rule of thumb is to set the overload at max motor amps (on motor plate) plus 10%.

It's not necessary these days, unless specified by the manufacturer, to add anything on to the full load current of the motor when setting overloads for DOL starters.

 

[Turbo]

It's not necessary these days, unless specified by the manufacturer, to add anything on to the full load current of the motor when setting overloads for DOL starters.

That's what I was taught when I was maintenance engineer 25 years ago, what has changed?

 

[Dave-sparks]

That's what I was taught when I was maintenance engineer 25 years ago, what has changed?

It depends on what the scale on the overload actually represents. On most overloads these days the scale represents the full load current of the protected motor, whereas many years ago it was more common to label them with the tripping current of the device.
Ultimately it does depend on what the scale has been calibrated for.

Like you I was also taught to set overloads above the rated current as an apprentice but then a few years ago I met an incredibly knowledgeable 'old-school' industrial electrician who pointed out that this was wrong and explained it all far better than I can.

Part of the reason came down to people's resistance to change and not keeping up with changes in technology.

I'd be interested to know when and why it became 10% above the setting current instead of the 25% that once was used if the scale is in actual tripping current?

 

[daleyd]

RTFM for whatever device you are using - some (admittedly not many) American overloads seem to still use the “add a bit” but the vast majority not. I seem to recall the European standard is a bit different, so most that you’ll see over here you just set to the motor plate.

Always worth a quick check though.

 

[Dave-sparks]

RTFM for whatever device you are using - some (admittedly not many) American overloads seem to still use the “add a bit” but the vast majority not. I seem to recall the European standard is a bit different, so most that you’ll see over here you just set to the motor plate.

Always worth a quick check though.

In the USA they are required by 'code' to overrate by a certain percentage, but none of them can explain why.

 

[daleyd]

In the USA they are required by 'code' to overrate by a certain percentage, but none of them can explain why.

I read into it on the destructions of an overload once (might have been Eaton?) - nema I think gives some options for service factor and suchlike which I don’t recall seeing in European spec stuff, but to be honest it’s been a long time since I’ve done anything with that…we tend to stick vfd on most things nowadays so it’s all a bit moot!

 

[Turbo]

TBH running any motor near its FLC for extended periods will likely shorten its life.
I used to see it in pressure washers where some 'expert' had fitted a smaller jet to give the washer more pressure. If they were lucky there was a current overload fitted that shut the motor off, though if they kept 'resetting' it the motor would eventually cook.

If they were unlucky & it was a cheap hobby washer there would be no overload fitted apart from the 13a fuse in the plug. Commonly the motor would be cooked before the fuse went!