Relation between Voltage and Frequency 1

[Rizgar]

Hello,

What is the relation between the voltage and frequency.
What will happen to a system if the frequency increased or decreased from it's rate frequency 50/60Hz due to any reason.

Thanks,

 

[peebee]

Q1 -- Generally none, they're rather independant. You've gotta put this in context, though. For example, if you're talking about the output of a generator, well, if the generator overloads then they will both droop together. If you're talking about motors & VFD's, you need to maintain a rather constant V/Hz ratio.

Q2 -- Depends on the system, how far you drift, and for how long. Some systems will run faster or slower. Some systems won't synchronize with other systems. Some systems will overheat. Some systems will draw more power. Some systems will go into alarm. Some systems will trip their circuit breakers. Some systems will go resonant. Some systems will explode. Some systems won't be affected at all.

 

[SidiropoulosM]

System frequency is affected by the imbalance between generation and load. If you have excess generation, system frequency goes up. If you have generation deficiency, system frequency declines.

System voltage is affected by how heavily the transmission lines are loaded. During light load periods ( e.g. at night) system voltage is high, because lightly loaded transmission lines behave as capacitors, generating VARS. During heavy load periods system voltage is low, because heavily loaded lines behave as inductors, absorbing VARS.

Can you have high frequency and low voltage? YES, when you have surplus generation online but the load is so high that the transmission system is loaded close or beyond its capacity, absorbing large amounts of reactive power.

Is there some coupling between frequency and voltage? YES, because reactive impedances are frequency dependent and impedances affect the voltage drop.

 

[jbartos]

Suggestion: Frequency relay, ANSI Device No. 81, will operate to protect frequency sensitive equipment and the system stability.

 

[boomsystems]

Voltage= 4.44*Flux*No. of turns*frequency

 

[jOmega]

When it comes to magnetics, consider the volt-time area as a limiting factor.

Cores designed for 50 HZ will have sufficient Volt-Time area to operate on 60 HZ without any apparent problems (all other things, including voltage, being equal).

However, the inverse is not true.... Cores designed for 60 HZ will have inadequate Volt-Time area for 50 HZ operation, ergo, they saturate on 50 HZ power, draw high current, and most likely will cook the insulation (boil the linseed oil out of the varnish)....