Y Delta Star and protection

[Patil]

I have star delta starter air compressor with 250Motor.Its new and first have only 3 leads coming out of the new cabinet.

I do have 400A HMCP.Im planning to use 350MCM cable from feeder to starter cabinet
Does this all help to protect motor and cable

 

[don_resqcapt19]

Assuming you are talking about the supply to the cabinet, the motor is 3 phase, 480 volt, and 250 hp, the NEC would require rated at 377.5 amps.

 

[Patil]

Sorry it’s 575V and FLC is 234Amps


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[Jraef]

I have star delta starter air compressor with 250Motor.Its new and first have only 3 leads coming out of the new cabinet.

I do have 400A HMCP.Im planning to use 350MCM cable from feeder to starter cabinet
Does this all help to protect motor and cable

You have a 400A HMCP in a factory assembled Wye-Delta starter? Because you cannot use an HMCP breaker as a feeder.

 

[Patil]

No the starter does have any disconnect or feeder.
We have 400A HMCP as a feeder and nothing else
I’m wondering we have to install a disconnect at the starter end and use the hmcp as feeder to feed the disconnect of the starter


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[retirede]

Because you cannot use an HMCP breaker as a feeder.

Does that also apply in Canada?

 

[Jraef]

Does that also apply in Canada?

Yes. It is essentially the same wording as in the NEC.

28-210 Instantaneous-trip circuit breakers (see Appendix B)
When used for branch circuit protection, instantaneous-trip circuit breakers shall be
(a) part of a combination motor starter or controller that also provides overload protection; and either
(b) rated or adjusted, for an ac motor, to trip at not more than 1300% of the motor full load current or at not
more than 215% of the motor-locked rotor current, where given, except that ratings or settings for trip
currents need not be less than 15 A; or
(c) rated or adjusted, for a dc motor rated at 50 hp or less, to trip at not more than 250% of the motor full
load current, or for a dc motor rated at more than 50 hp, to trip at not more than 200% of the motor full
load current.

 

[petersonra]

You have a 400A HMCP in a factory assembled Wye-Delta starter? Because you cannot use an HMCP breaker as a feeder.

Where does the code say it has to be factory assembled?

I don't think there's any prohibition against having an MCP in a separate physical location from the contactor or starter.

 

[Jraef]

Where does the code say it has to be factory assembled?

I don't think there's any prohibition against having an MCP in a separate physical location from the

In re-reading the CEC section, you may be right. In the NEC, it is more explicit in 430.52.C.3.

Instantaneous Trip Circuit Breaker. An instantaneous trip
circuit breaker shall be used only if adjustable and if part of a
listed combination motor controller having coordinated motor
overload and short-circuit and ground-fault protection in each
conductor, and the setting is adjusted to no more than the
value specified in Table 430.52.

We say "listed" and I have always interpreted this as meaning listed by the starter mfr, because they must be tested as a set of specific components to be listed. If you ever look at an MCP breaker, they are never UL listed, they are only UR (Recognized Components) that must be used in specific tested combinations. CSA might be different though.

 

[paulengr]

MCP is a Listed component, not an assembly. So you can only use it as part of a factory assembly or as replacement in kind. This is UL or cUL or CSA. It’s not really CEC or NEC. This two level component vs assembly difference is an NRTL thing. An MCP I sn’t Listed for end use. In a jurisdiction where Lustung is not required such as military, utilities, or mining (Canada has their own M421 mining Code) Listing is not required and there are no problems using an MCP. As far as rating as long as it meets or exceeds the ampacity requirement and can hit the required short circuit rating (only thing that matters) it will work.

 

[Patil]

I do think MCP can be used. This is feeding the compressor from 20mtrs far.
The compressor star delta starter has the overload and fuses.
So it have all protections.

I was thinking about protection of cable from starter to the feeder.
MCP just has instantaneous settings only


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[kwired]

I do think MCP can be used. This is feeding the compressor from 20mtrs far.
The compressor star delta starter has the overload and fuses.
So it have all protections.

I was thinking about protection of cable from starter to the feeder.
MCP just has instantaneous settings only


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Short circuit ground faults are taken care of by the instantaneous trip device. Overloads are taken care of by the motor overload device. You will never overload it unless you tap something else other than the motor to it. Even with thermal magnetic devices it generally works this way because they are oversized to allow across the line motor starting.

 

[Patil]

Instantaneous tripping is not for ground faults as the fault level is lower.Instantaneous is set for 1300%


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[petersonra]

I do think MCP can be used. This is feeding the compressor from 20mtrs far.
The compressor star delta starter has the overload and fuses.
So it have all protections.

I was thinking about protection of cable from starter to the feeder.
MCP just has instantaneous settings only


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I think you might be right. My personal opinion is that there is no requirement that a UL listed combination starter be factory assembled or that it be in the same enclosure unless UL says it has to be as part of the listing arrangement. Otherwise, you would not be able to assemble a starter from a contactor and overload relay.

 

[kwired]

Instantaneous tripping is not for ground faults as the fault level is lower.Instantaneous is set for 1300%


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If you are talking about lower level detection that is detected by GFCI's or GFPE's yes. A direct ungrounded conductor to ground(ed) conductor fault should draw high level current and should trip an instantaneous trip device in most cases.