Fail Safe Terminology

May I put a counter question? What is the plain dictionary meaning of "fail safe start command."

Dear Joshi..

Please note that Fail safe in Electrical system can explain like this

Fail safe equipment if fails than also there is no harm or it is safe.The couples eg are-

1) Stop command is always "open to stop type" i.e. "in Electrical Control ckt "NC contact is used of Pushbutton). SO that in event of failure of stop Pushbutton element or damage of remote cable core (incase remote Start /stop is anticipated ) the Motor /equipment shall stop automatic or Motor /equipment cannot be started again as per safety aspect.

2) In case of Electromechanical Brakes of 24V/110V/220V D.C in system brake is released when the Coil is energies & Brakes shall be engages when D.C supply is disconnected. In case if coil failure also the brake will be engages.

There are many eg of that kind.

I hope it is clear to you.

Similarly for the DG start what ???

( Since DG should always start in the event of Power fail) but how ???

Regards

Rodrick

Thank you, rodrick. I follow you now.

The link DNV-OS-A101 posted else where, is not exactly what you are looking for. But it is about the 'fail safe principle' Please see under SECTION 5 EMERGENCY SHUTDOWN (ESD) PRINCIPLES, C. Fail-Safe Functionality.

The following link may help you.

DNV-OS-A101: Safety Principles and Arrangements - DNV Exchange

Rodrik

From the definitions so far obtained for 'Fail Safe', it seems that, here, it might mean:

"The starting contact does not need a powered device (like a relay or contactor) to be energised before making and starting the DG" (?)

i.e. When there is power failure, a coil is released and a N.C. contact on this coil, will start the DG engine.

Does it make sense ?