What is an AMF Panel? | Automatic Mains Failure | how it work

amf panel

AMF Panel stands for Auto Mains Failure (AMF) Panel. In commercial terminology we use this name for a system which does changeover of one Mains source and one DG source.

AMF may constitute of following hardware:

  • Fuses/Isolator/MCCB/MCB/ACB/ as incomer switch/ protection for Mains supply and DG supply.
  • Contactor/Motorised changeover/ ACB / Motorised MCCB for changeover
  • AMF controller/ Timer logic for changeover command changeover system.
  • DC relays for ON/ OFF operation of DG
  • Protection relays for DG and Mains
  • AC, DC metering for Mains and DG.
  • Audio and video annunciation for various faults of DG.
  • Wiring, busbar, Enclosure, etc.

Step wise operation of AMF Panel is as follows:-

  1. In case of Mains supply failure AMF Panels send a start command to DG after a set time delay.
  2. When DG comes to generate its rated voltage i.e. it satisfactorily starts then after a set time delay AMF panel does changeover of Mains source to DG source via Contactor/Motorised changeover/ ACB / Motorised MCCB.
  3. When Mains supply restores then changeover takes place instantly and AMF panel changes source back to Mains supply.
  4. It send close command to DG after set time.

AMF Panel can be loaded with some extra features/ protections which are as follows:

  • Dual source/ single source KWH Meter for KW metering of Mains/ DG.
  • Frequency meter, Power factor meter, Multifunction Meter based on customer demand.
  • Common fault protections such as Overload, Over/under voltage, Over/under frequency, Phase sequence, Reverse power, Earth fault etc.
  • Advance protections such as Restricted earth fault, Generator differential protection, IDMT overcurrent earth fault relay, Master trip, Field failure relay, Vector shift relay, trip circuit supervision, etc.

Ambiguity in AMF panel working:-

On return of Mains power supply either Mains source should restores instantly or it should take some time. Why I am asking this because sometimes mains supply can fluctuate and instantly changeover can cause malfunction the system by fast repeated changeover. Also waiting after Main supply restorations is also not a right practice.

Leave A Comment