IMHO that is not very good solution since the transformer will be subjected to frequent inrush currents and hence frequent mechanical stresses. I think it's lifetime will be reduced.
Why not to switch the secondary side of the transformer?
Just for information - in Russia MV networks are 6kV, 10kV and 35kV (50Hz) networks, and almost all of them are isolated from earth.
Networks above 35kV (that is 110kV, 220kV, 330kV etc) are so-called "effectively-grounded" - i.e. they are grounded via small impedance, almost solidly.
Networks...
Itsmoked: agree to negative sequence and strongly disagree to 160% and losing its speed. When the load is low or in the idle mode there can't be 160% even if the phase failure occurs. The speed also can't change much in the idle mode since the rotor tends to run after the positively rotating...
Let us assume the following situation:
- a three-phase motor is running with two phases only (one of the phases was opened somehow after it was successfully started) and its speed is approx rated (no starting issues),
- its stator current is: Line1 = 100% of FLA, Line2 = 100% of FLA, Line3 = 0%...
www.ld-harvest.com is not the only one so similar to Robicon. There are also:
www.yaskawa.com
www.rxpe.com
www.tmeic.co.jp
The last one did installed its MV drive in Russia in the city of Toliyatti. I heard there were problems with those drive on the 4th day after start-up due to power cell...
ScottyUK, thanks a lot.
Skogsgurra, You mentioned that Rogowski Coil has no leakage reactance.
I looked through the operating principle of this device again and I came to conclusions that:
1. Actually there is leakage reactance in the secondary of the Rogowski Coil but since secondary current...
"The CT will struggle below nominal frequency at rated current because of core saturation"
That has made a lot of sense to me. I thought through this idea and I had a question to it: does the degree of saturation depends on the secondary circuit ohmic resistance? I mean I came to a conclusion...
Hello everyone,
Would You please explain the following: we have a conventional current transformer (CT) and we have a Rogowski Coil Current Sensor (RCCS). Both use the same principle - Faradey's Law, right?
Then why do we have such a narrow frequency range for CT - just 50/60 Hz, while RCCS...
I had an experience with ROBICON Perfect Harmony (6kV/1250kW) here in Russia. What can I say? It works exactly as declared by ROBICON. (Now it's SIEMENS, but who cares?) Anyway it seems to me as a very good drive, but the production takes a good deal of time and cost is very high.
What exactly...
