hello, where do we need to connect the current transformer on pfc installations which gives the current knowledge to the reactive power relay ,in fornt of the power transformers or to the load side of it? ? am asking it because i cant guess the role of the reactvie power due to the magnetization of the power transformer
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PFC
- Thread starter turkoman
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Hi,
Hope I understood a question. There are two important and DIFFERENT issues concerning automatic pfc:
1. connection point of CT supplying relay/controller
2. connection point of capacitor bank (reactive current injection)
Speaking of transformers, it is a practice that CT is connected at same voltage level as capacitor bank. Otherwise, u need to take into accout transformer ratio by multiplying it with CT ratio, which is bad and sometimes impossible solution. So, if u have a LV capacitor bank,u live no load (magnetization) transformer power uncompensate automatically, but u can install some fixed bank for no load compensation and combine it with automatic. Most European manufacturers (I worked with Ducati and SE) provide controllers that calculate with sum of load current and capacitor bank current, so u have to connect CT upstream of cb connection point. That point (cb connection) shold be upstream of load u wish to compensate, but downstream of measuring point, otherwise u will compensate reactive power for ur distribution company, but with no cost savings for u
Hope this will help.
Speaking of CTs...I have a question too. We know for Fs and thermal factor/class, but they apply to current overload capacity. Can we, however, use the same CT on different VOLTAGE level? Any practical experience?
Kind regards,
MikiBg
Hope I understood a question. There are two important and DIFFERENT issues concerning automatic pfc:
1. connection point of CT supplying relay/controller
2. connection point of capacitor bank (reactive current injection)
Speaking of transformers, it is a practice that CT is connected at same voltage level as capacitor bank. Otherwise, u need to take into accout transformer ratio by multiplying it with CT ratio, which is bad and sometimes impossible solution. So, if u have a LV capacitor bank,u live no load (magnetization) transformer power uncompensate automatically, but u can install some fixed bank for no load compensation and combine it with automatic. Most European manufacturers (I worked with Ducati and SE) provide controllers that calculate with sum of load current and capacitor bank current, so u have to connect CT upstream of cb connection point. That point (cb connection) shold be upstream of load u wish to compensate, but downstream of measuring point, otherwise u will compensate reactive power for ur distribution company, but with no cost savings for u
Hope this will help.
Speaking of CTs...I have a question too. We know for Fs and thermal factor/class, but they apply to current overload capacity. Can we, however, use the same CT on different VOLTAGE level? Any practical experience?
Kind regards,
MikiBg
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