Inverse Time Undervoltage Formula
Inverse Time Undervoltage Formula
(OP)
Guys, this may be a dumb question to make but I would appreciate if you will provide me a better understanding.
A G.E. Manual states that its undervoltage delay settings defines the family of curves shown below:
T = D / [1-(V/Vpickup)]
where T = operating time
D = Undervoltage Delay Setting
(D = 0 operates instantaneously)
V = secondary voltage applied to the relay
Vpickup = Pickup Level
Looking at the sample graph, for D = 2 and %voltage pickup of 2%, the operating time is approximately 2 seconds. I'm a little confused on what values I would use for V and Vpickup to coincide with the graph below:
[IMG]http://i53 2.photobuc ket.com/al bums/ee327 /primo_bel tran/Inver se_time_UV _curve.jpg[/IMG]
My application is for a 120VAC secondary and with a target operating time of 3 seconds...what will be the Delay setting (D)?
A G.E. Manual states that its undervoltage delay settings defines the family of curves shown below:
T = D / [1-(V/Vpickup)]
where T = operating time
D = Undervoltage Delay Setting
(D = 0 operates instantaneously)
V = secondary voltage applied to the relay
Vpickup = Pickup Level
Looking at the sample graph, for D = 2 and %voltage pickup of 2%, the operating time is approximately 2 seconds. I'm a little confused on what values I would use for V and Vpickup to coincide with the graph below:
[IMG]http://i53
My application is for a 120VAC secondary and with a target operating time of 3 seconds...what will be the Delay setting (D)?






RE: Inverse Time Undervoltage Formula
Since Vpickup is expressed as a percentage in the graph, V=100% (of 120V) in the formula above.
RE: Inverse Time Undervoltage Formula
Its 85% nominal volts (120VAC) for 3 seconds.
RE: Inverse Time Undervoltage Formula
RE: Inverse Time Undervoltage Formula
RE: Inverse Time Undervoltage Formula
Is it acceptable to set a 0.85P.U. voltage pickup using a DEFINITE time of 2 seconds instead of using an inverse voltage curve?
RE: Inverse Time Undervoltage Formula
RE: Inverse Time Undervoltage Formula
RE: Inverse Time Undervoltage Formula
Pay attention on the RCWilson recommendation.
I agree 3.
Best Regards.
Slava
RE: Inverse Time Undervoltage Formula