DG running at unity power factor

Unsure what happened, my reply Post did not "Register", so I went back in my Browser, and Copy/Paste it here:

I presume your DG refers to a Diesel Engine with a 1.01MVA Alternator running mechanically from that engine.

It is impractical to try and correct the Power Factor at the Alternator end.

It is also extremely expensive to actually obtain a unity Power Factor, the best cost/value is around 0.95.

The reason it is far more efficient, and cheaper, to put the PF correction at the user end (motor/welder/etc) of the circuit, is because of the reactance in the transformers and distribution network.

Thus rather than having all those out-of-phase currents all coming back to the Alternator, with the extra heat in the transmission system, they take the shorter circulating paths to the local PF correction capacitor/s.

In the case of long transmission lines, at high voltages, and 30+ MVA transmission, it is often the practice to use a "Synchronous Capacitor" at the end of the line, where it enters the substation for a city/large factory etc.

The "Synchronous Capacitor" looks like a very large electric motor, and because the exitation of the wound rotor can be varied either manually or automatically, the PF correction can easily take place at the load end of a 100+ km transmission line.

With your small unit, depending on your transmission/load arrangements, if the motors/welders are close together, the cheapest/most efficient option is a single automatic static PF correction unit, controlled by a semiconductor sensor and amplifier.

If your load devices are far apart physically, then the most efficient/cost effective way is to have PF correction applied at the terminals of each device/motor/welder etc.

Both above static types are commercially available....

This topic has been dealt with in detail previously.Please go through the previous postings.You will get answers for your doubts.

Hello ramvinod,

The person who wrote several vague questions yesterday, wrote 2 identical questions, but when I looked for my answer to the first question, it wasn't there, because I was looking at the other identical question, but I did not realize that at the time.

Several questions were asked at the same time, all poorly formulated and almost impossible to answer, looked like Homework enquiries, or "Impossible Questions".

After trying to answer some of the Poster's questions, I realized there was no easy way out, and requested the Topic Poster to reply, with questions asked in a manner in which they could be actually answered.

There has been no reply from the Poster of those Topics....

Kind Regards....