Please don't laugh..where does an ATS get its power from?

[Installer]

Where does a Transfer Switch get its Power?
In the diagram below, we are doing work on both the Main Critical Panel (ELPA) and the Main Normal Panel (MDPN).
I'm going to have the Utility come in and shut down the Utility Feed at the Transformer.
I'm also going to lock out the Emergency Generator (EDG)

From the One Line I believe the ATS is powered by through the Normal Panel MDPN.
So when we remove power from that Panel, what gives the ATS the power to switch to Diesel (EDG) ?
Of course it does, but I'm just curious where the power comes from.

The thing here is that we have an ASCO KBC-DCVA-0260S Microprocessor controlled ATS that doesn't have one of those big manual safety handles for Maintenance
that you can open and isolate everything and completely make the Input and Output of the ATS safe. So I have to lock out the EDG to make everything safe

So I'm curious when the ATS loses power, where does the ASCO KBC-DCVA-0260S Microprocessor controlled ATS get its juice form? Will we have a dead microprocessor controller?

When does it become active again? When power is restored at the Utility?

 

[Hv&Lv]

1

 

[infinity]

So I'm curious when the ATS loses power, where does the ASCO KBC-DCVA-0260S Microprocessor controlled ATS get its juice form? Will we have a dead microprocessor controller?

When does it become active again? When power is restored at the Utility?

Typically the ATS transfer function receives power from the emergency source. There's a N/C contact in the ATS that closes when it loses normal power which starts the generator, when it senses an EM source it uses the EM power to transfer.

 

[Jraef]

Typically the ATS transfer function receives power from the emergency source. There's a N/C contact in the ATS that closes when it loses normal power which starts the generator, when it senses an EM source it uses the EM power to transfer.

Correct.

You seem to be thinking that the ATS must "power" the generator up. All it does is close a contact in the generator's starter system. Think in terms of a key switch for your truck engine. It's just a switch going to a small solenoid in the starter motor; the power to start the engine comes from the starter battery. Once the engine is up and running, supplying power, then the ATS uses that power to change over.

 

[mbrooke]

My understanding is that utility power transfers the ATS back. If I remember right NFPA requirements state that if the gen dies while in Emergency, the ATS must transfer back to normal if any one phase is energized.

 

[Installer]

thank you very much!

 

[Installer]

Wait a minute. With Utility power down and the EG out of service, how does the Microprocessor controlled ATS unit get its power?
This is not a manual unit with a knob or lever that I trust

 

[LarryFine]

As an example, I believe Generacs use the 12v starter battery for control, too.

 

[Installer]

Thanks--I got off the phone with the Rep, its got a Battery and Microprocessors dont use much pwer.

Thanks for your help everybody!

 

[steve66]

My understanding is that utility power transfers the ATS back. If I remember right NFPA requirements state that if the gen dies while in Emergency, the ATS must transfer back to normal if any one phase is energized.

Yes, if the generator dies, the ATS must switch back to utility if there is utility power. I believe ASCO ATS's usually use generator power to switch to generator, and utility power to switch back to utility. That way, the ATS won't ever switch to a dead source, even if the microprocessor went berserk.

 

[Russs57]

Actually, on the new Asco's, if the microprocessor brain dies, it is perfectly happy to stay connected to a dead bus even if a live one is present.

Back to the original question. You stated both MDPN and EDG will be down. In that case you will have no source of power for the ATS to transfer to.

Start signal to emergency generator is from a relay that changes state upon loss of normal power. It needs no power to become de-energized. Power for starter solenoid on generator is from the generator battery. Things can be done differently, such as when the diesel generator has an air powered starter motor.

 

[mbrooke]

Yes, if the generator dies, the ATS must switch back to utility if there is utility power. I believe ASCO ATS's usually use generator power to switch to generator, and utility power to switch back to utility. That way, the ATS won't ever switch to a dead source, even if the microprocessor went berserk.

Good to know my memory is correct.