V/HZ ratio?
V/HZ ratio?
(OP)
What is significance of Volts / Hertz settings in AVR. And what are the typical settings for large generators?
Thanks in advance.
Thanks in advance.
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RE: V/HZ ratio?
http://www.basler.com/html/rscreg.htm
and
Reference:
1. IEEE Std 242-2001 (Buff Book)
Section: 12.5.5.4 Overexcitation protection beginning by page 485.
V/Hz = 1.05 per unit for a generator (i.e., generator base) and above causes the generator and associated transformer overexcitation
Also, when generator operates at lower speed V/Hz ratio is monitored to protect the generator and load.
RE: V/HZ ratio?
For one of my generators;
13.8kv/60 = 230volts/Hz
What this does is provide a 'sag' to the AVR such that the motor or generator does not go into over saturation.
The reason that I mention motors is that it also applies to VFD's as well.
RE: V/HZ ratio?
At the moment i don't remenber typical curves and settings for this protection, but i will investigate.
RE: V/HZ ratio?
Overexcitation protection rationale is hashed over in IEEE Std C37.102-1995 §4.5.4 for Generators and IEEE Std C37.91-2000 §8.2.4 for Transformers.
RE: V/HZ ratio?
We have a 15.5 KV rated generator at 50 Hz. The alarm on overvoltage is set at 16.2 KV. Tripping stage one is 17.02 KV for 10 sec and 20 KV instantaneously.
Actually i wanted to know that before the tripping voltages are acheived, what will be the role of VPFL, volts per freq limiter? What does it do as part of AVR. What are the alarms settings of VPFL typically and whats the ratioanle.
V/F is usually taken as ratio of per unit voltage to per unit frequency. E.g., frequency is at 50.5 Hz, when will V/F limiter operate?
Also as i dont have access to IEEE standards, i cannot get further information from the reference. Unless someone can send me excerpts or the standard to me at irfan.akhtar@elpaso.com
Thanks in advance.
RE: V/HZ ratio?
It was not possible to tell from the original post which standards were applicable to the subject generator.
Most IEEE standards are available online or emailed PDFs, but access is fee based. Given the followup information supplied, they may have limited value to you.
RE: V/HZ ratio?
http://www.geindustrial.com/products/presentations/dgp/dgp.pdf
for Relay 24 on page 6 graphical setting
RE: V/HZ ratio?
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