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Old November 29th, 2017, 07:03 AM   #1
AustralIan
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Star Delta Starter with Timer Relay or with PLC Timer

Star Delta Starter with Timer Relay or with PLC Timer.
Any preferences?
Any reasons one way or another?
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Old November 29th, 2017, 07:07 AM   #2
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It is really up to you and the functionality of the system.

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Old November 29th, 2017, 07:31 AM   #3
slp530
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A mechanical star delta time has a small time delay between the Star-delta changeover also use mechanically interlocked contractors for Star delta
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Old November 29th, 2017, 07:56 AM   #4
renan.musardo
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Quote:
Originally Posted by AustralIan View Post
Star Delta Starter with Timer Relay or with PLC Timer.
Any preferences?
Any reasons one way or another?
If I already had a PLC, I'd use the PLC timer instead of a timer relay.
But it really depends on you. The final result will be the same.
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Old November 29th, 2017, 11:31 AM   #5
moggie
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Quote:
Originally Posted by AustralIan View Post
Star Delta Starter with Timer Relay or with PLC Timer.
Any preferences?
Any reasons one way or another?
Timer relay - anyone can change the time delay without the need for software or interface cables.
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Old November 29th, 2017, 11:50 AM   #6
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Quote:
Originally Posted by moggie View Post
Timer relay - anyone can change the time delay without the need for software or interface cables.


The transition time is more of an art than science, because the load on the motor makes a difference. You want that to be easy.

And as said earlier, there are really TWO time delays involved in a Star-Delta transition timer. Electro-mechanical timers do it via contact operating times, electronic S-D timers have to emulate that, which is not a simple thing in a PLC. Not impossible, but you have to fully and deeply understand the process. Not enough or too much of an open transition time can cause severe damage, both electrically and physically. I've seen open transition problems cause a 500HP motor shaft to shear off.

That's also why I never use S-D any more, I use RVSS starters.
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Old November 29th, 2017, 11:55 AM   #7
Ronnie Sullivan
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Plc timer every time
Use mechanical interlocks and inputs from the n/c of star and delta.

It's not often a timer needs adjusting once set correctly.
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Old November 29th, 2017, 01:22 PM   #8
Gene Bond
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Originally Posted by jraef View Post
That's also why I never use S-D any more, I use RVSS starters.


If I had to use one, I'd go with a separate timer, so *when* the PLC has to be bypassed for whatever reason (with an HOA switch or whatever), I could still safely start the motor...
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Old January 7th, 2018, 03:34 PM   #9
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Thanks all, I think I like the idea of a PLC timer with mechanically interlocked contacts best, but in the end it is probably not priority 1 at the moment to evangelise either way.

Agree with RVSS for higher kW applications.

My new years resolution is to phase out imperial measurements, especially the mile, which I will be replacing with 1.852km, unless the person specifically tells me they are working with the international mile.

I am also going to assume metric horsepower, ie. the power to raise 75kg by 1m in 1 second under 9.80665 N/kg of gravity.
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Old January 8th, 2018, 06:25 AM   #10
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I would agree with jraef for sure regarding RV starters over S - D. I worked for a large water utility for 10 years out west, and we had mostly 5kv motors with RVAT starters. The transition, incomplete sequence, etc. used relays. A-B made a good one. We re-wired a lot of them to transition on current using a GE Multilin 469 MPR. It has a lot of capabilities that certainly surpass relay logic, but it is quite expensive.
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Old January 8th, 2018, 10:40 PM   #11
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Quote:
Originally Posted by AustralIan View Post
Thanks all, I think I like the idea of a PLC timer with mechanically interlocked contacts best, but in the end it is probably not priority 1 at the moment to evangelise either way.

Agree with RVSS for higher kW applications.

My new years resolution is to phase out imperial measurements, especially the mile, which I will be replacing with 1.852km, unless the person specifically tells me they are working with the international mile.

I am also going to assume metric horsepower, ie. the power to raise 75kg by 1m in 1 second under 9.80665 N/kg of gravity.
What is this wicked metric heresy speak.....LOL
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