LV reactive energy compensation

[rzgpp]

Most of companies which work on this field,talks about inductive energy compensation.Most of solutions are based on condensator switching controllers.I understand that this is most common,but what about compensation of capacitive load?How is switched reactor?What kind of controllers are used?Did somebody do this type of compensation on LV to clear for me?

 

[waross]

Capacitive loads are rare.
Capacitive loads without an offsetting inductive load a fewer still.
Do you have a specific application?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[dpc]

Shunt reactors are used at medium voltage to counteract long cable runs at light loads. I've never seen this done at low voltage for the reasons given by waross.

 

[cuky2000]

There are a couple of factors that drive the needs of reactance compensating in an electrical system, primarily focus on LV applications as follow:

1) LV feeders are fundamentally resistive and somehow the feeder length is mainly dominated by voltage drop limit in contrast to HV feeders. Occasionally MV feeder is long such radial distribution feeders or offshore wind farms applications that may need reactance compensation at both ends to mitigate the charging capacitive current.

2) Cable Insulation thickness act as a natural capacitor on cable. However, for LV cable large capacitance is a non-issue since the insulation thickness is fairly small compared with HV and MV cable insulation.

Below is a graph with indicating a typical critical distance for HV & UHV application. Notice that for 132 kV the critical distance is around 136 km (~85mi). For MV, this critical distance will be larger and unlikely a practical application for LV systems.

Hope this helps.

>>>>>>>

 

[rzgpp]

It is very expensive to make compensation in MV.My case is 3km MV cable..and far away small transformer 75KVA...most of time light loaded.When it is loaded...there is no capacitance...or it is small compared to apparent energy....and I need to comutate at that moments reactor on LV side....reactor for LV is cheaper...but how to switch it....?Contacot for heavy inductive loads?Thanks all!

 

[bacon4life]

A run of 3 km is small enough amount of cable that voltage rise and excess current flow should not be issues. Why do you need to compensate for it? If this is just for power factor billing, be sure you understand exactly how the utility calculates power factor billing. Some utilities totally ignore leading power factor for billing purposes.

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