Motor Control equipment 4

[ian4340]

I have a motor 1.5Kw 415v 3PH 50Hz 4.3A.
I also have a control panel from an old machine which I wish to use, the panel has a manule motor start & a contactor which I need to upgrade.Can anyone give me info on sizing the manule motor start & contactor.
I wish to keep with this system to avoid fuses & overloads.
Any help would be grate,
Thanks IAN

 

[jraef]

Um, buy a contactor and manual motor starter rated for at least 1.5kW at 415V? What is the problem here?

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[ScottyUK]

"avoid fuses and overloads"

To what end? These are protective devices which serve to protect equipment and personnel. Why do you want to avoid using them?



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But with my luck, I'll be at the airport!

 

[jraef]

Holy frijoles. I missed that ScottyUK!

However, a manual motor starter should include overload protection by definition, and a circuit breaker would be an alternate to fuses. IEC motor protective switches combine both features I suppose, but they need to be backed up by fuses in most cases.

 

[itsmoked]

Scotty surely you jest... fuses and overloads have killed more motors than all the abuse ever dished out to the motor shafts...

Overloads and fuses are so bad that not a single refrigeration equipment manufacturer allows them, period!

"Any use of motor starters, mag switches, or fuses voids warranty" Is generally how it's written.

We have seen literally hundreds of motors that have be destroyed specifically by motor starters with "heaters" and fuse(so called) protection.

The refer companies like Carrier actually provide "the" required circuit breakers. Often you will get a breaker from them that is rated at some strange value like 56.7A.

Obviously ian4340 has seen the havoc dished out by these lousy devices as have I.

Can we could suggest some of the newer protections that are available?

 

[dpc]

smoked,

I'm not sure I understand the concern. The vast majority of 480V three-phase motors in the US are protected by contactors and heater-type overload relays in series with a molded-case thermal mag breaker, a mag-only (MCP) breaker or a set of fuses.

Are you saying that a circuit breaker will provide superior protection to a motor over an overload relay? What is the basis for that?

 

[jraef]

I think (or at least hope) that itsmoked was being his jovial sarcastic self.

 

[itsmoked]

Nope. I'm sorry, not being sarchastic.. I knew this would open a can of wormies.

It of course depends on the application. For a 5-10hp motor running an air or refrigeration compressor I would use anything BUT heater-type overloads. I have seen so many that have damaged the motors under their protection. As I mentioned, so have whole industries, like refrigeration. They are so bad I've started thinking they were created for service companies to make money with. They need to have their screws checked often. They get warm and corrode. Often when malfunctioning they resort to causing single phasing.

This is as relates to all the ones I've seen. I haven't come across the new ones with blade heaters etc. etc. Maybe they work okay.. I have no direct experience with them.

I can say it is very, very, hard to tell the owner of a Maw&Paw grocery store that they need a new $1,500 compressor because the protection device fried it. They get kinda .

Also fused service disconnects cost way too much for what you get,(regular single phasing!), compared to a pure disconnect.

If I were ian4340 I would use a non-fusible service disconnect and a breaker on that motor. I would however go to the effort to find a HVAC breaker!

If I wanted more protection I would use a motor monitor to condition a contactor.

Something like:

http://www.ab.com/en/epub/catalogs/12768/229240/229258/3170949/1521151/

I'm sarcastic!?!? hahaha, lolo, I thought I was less so than jraef!! hehehe. I've been trained because my wife doesn't take to my rare(?) sarcasm too well. She breaks out her lethal elbow-to-the-gut move.

 

[ian4340]

Hay Get a grip! simple question info on sizing?
My panel is small very well made has all outher equipment I need no room for adding. The panel has a GEC 63A short circuit protection & 6.3-10A overload protection switch the contactor is a GEC 12A I wish to replace with the same unites sized for my motor.
Thanks Ian non electrical Eng!!!

 

[ScottyUK]

You'll be lucky to find GEC control gear these days. I'd personally use a contactor and overload from Siemens. There are other brands obviously, but I've found this range is of better quality than some well-known European brands (one that starts Tele... for example). Siemens part numbers to suit your motor are below:

Contactor
3RT10 15-1AB01 24V AC coil
3RT10 15-1AF01 110V AC coil
3RT10 15-1AP01 230V AC coil

Overload
3RU11 16-1GB0

You should reduce the size of the fuses to a 20A gL/gG type. A 63A fuse has too large an I[sup2[/sup]t let-through for a contactor of this size.



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One day my ship will come in.
But with my luck, I'll be at the airport!

 

[jraef]

Well, the contactor size is fine, no need to replace it if it works, but you will need a new MPS that can be adjusted down to the 4.3A of your motor. One brand is as good as another in my opinion, so the criteria should be who you have readilly available to you. ScottyUK is right, GEC has all but disappeared as far as low voltage controls go, so Siemens is as good a choice as any. Not much chance of them going away in our lifetimes.

Here is the Siemens MPS product line (US website). They call it a Motor Starter Protector (MSP) Siemens MSP link I would get the 3RV10 21-1FA10. That would be your short circuit and overload protection device, adjustable between 3.5 and 5 amps. This is not an endorsement, just a shortcut because I happened to have that available. Almost all other IEC component makers offer the same type of devices, and all of them are good enough. There are rules about maximum fuse sizes or current limiters necessary upstream from these devices, but it sounds as if this is what you had from GEC, so if it was OK for that unit, this is most likely OK as well. Just check it out based on your local codes before using it.

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[ScottyUK]

I[sup2[/sup]t should have been I²t. Careless of me!


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One day my ship will come in.
But with my luck, I'll be at the airport!