Automatic Mains Failure Panel – How do they work?

/Automatic Mains Failure Panel – How do they work?
Automatic Mains Failure Panel – How do they work?2020-05-07T05:38:13+00:00

The Automatic Mains Failure ( AMF) Transfer Panel is used to switch the electrical source between the utility mains GRID supply and a Standby Diesel Generator supply.
Moreover, for genuine Power Control,
there must be a UPS system that sits between the GRID supply and the emergency standby diesel generator.
Hence, when  GRID power fails, replacement power is seamless NO BREAK transfer to emergency power systems.

How Automatic Main Failure (AMF) Panels Work

Under normal circumstances the UPS system will derive its supply from the utility mains supply.
Dependent upon the sophistication of the Automatic Mains Transfer Panel there will be a number of different sensors for determining a loss, partial loss, or variation of the utility mains supply.

AMF sensors

The most basic sensors are utility mains failure sensors.
These sense anything from a single phase of a three-phase system failure to all three phases failing simultaneously.
Detection of these failures is often achieved by voltage sensing relays which will operate when the utility mains has reached a predetermined point of failure.
Settings should be adjusted in conjunction with the operating characteristics any uninterruptible power supplies in mind.
Warning point to be aware of, is be careful incase the utility mains failure is outside of the UPS systems operating parameters.
Dangerously if that is the case, your load is being supported by the UPS batteries while the standby diesel generator is lying idle.
Regular service and maintenance will highlight such issues and provide options to fix.

AMF Contactors

In its simpler form the Mains Transfer panel consists of two contactors with their associated control sensors.
One contactor will supply the utility mains source to the site distribution board.
Whilst the other contactor will supply the standby diesel generator supply to the distribution board.
During a utility mains failure, initially the mains contactor will de-energise and Automatic Mains Failure (AMF) Panel.
Immediately thereafter send a start command signal to the emergency standby diesel generator to start up and accept building load.

Once the standby diesel generator control sensors have determined that the generator supply is at the correct frequency and voltage a signal will be sent to the standby diesel generator contactor to energise it and fed the generator supply to the site distribution board. Check out our monitoring pages.

When the utility mains supply is re-established a timer will start to ensure that the supply is stable.
Thereafter follows a preset time the utility mains contactor will energise and the standby generator contactor de-energise.
The standby diesel will continue to run until it has cooled down. Usually 5 minutes and then the generator switches off and is ready for future action.

During the GRID power outage, ( Loss of the utility mains supply),the standby diesel generator the ups system will seamlessly provide your the essential power. Just remember never to let the diesel generator run of fuel. Obvious? Don’t you believe it!
Our most frequent call outs are to generators that have been allowed to run out of diesel.

For timing purposes, the duration of supply loss between the failure of the utility mains supply and the provision of a supply from the standby diesel generator can be as short as 10 to 30 seconds.
Providing that the generator starts first time. This depends on your regular service & maintenance regime.
Returning to the utility mains supply the changeover time can be measured in mille-seconds.

And then commercial  life and power goes on as before.


How an Automatic Mains Failure (AMF)  panel works?


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