Hello!
I have a load supplied with 2 cables in parallel per phase and I had to use 1000A/ 690V fuses in order to protect the cables for short circuit. These fuses are hard to find - not on stock, anyway - and size is 4a. Can I use instead one fuse for each of the 2 identical cables in...
I wonder if anyone has an idea about how to protect/ improve maintenance performance for three phase contactors used with shunt reactors. My circuit voltage is 3x660V and I'm using multiple steps with shunt reactors, switched ON and OFF by air type contactors in order to regulate the power...
Hello!
I wonder if someone on the forum knows the role of the second much smaller reactor in series connection with each branch of TCR reactor. The TCR reactor is made up from 3 air core reactors - one for each phase. Each phase reactor is devided into 2 equal halves but - at least for this...
Hello!
I want to ask you about surge protection for three phase shunt iron core reactor on medium voltage (20kV). I want to use surge arresters and surge capacitors. My problem is that there are 3 single phase reactors which I must connect in wye connection in order to have a three phase...
I have a problem regarding one client who ordered inverter and motor from different manufacturers and not matching characteristics. The inverter is for 315kW/ 3x400V, 50Hz asynchronous motor but the current capability (616A) and kVA rating are under what the supplied electric motor needs. It is...
Hello!
I'm looking for hints on how to design the RC protection for large motors started and protected with vacuum breakers. I have read that together with surge supressors there is a need for RC group surge protection to limit the steepness of voltage rise.
I know that usually you have to make...
Dear all,
I have to design a 9500A, 7.2kV bus bar. There is an existing 7500 bus bar but I think that I have no possibility to upgrade it to 9500A. From the ABB switchgear manual I found out that U shaped aluminium conductors arranged face-to face are the most suitable for the job - the existing...
Hello!
I wonder if someone can help me with tips/ document about choosing a suitable current transformer for a protection application - short-circuit close to generator - where the load current is 1000A, Ik'' = 30kA and Ipeak = 80kA. I need to choose according to IEC.
Thanks!
Pafi
Hello!
I would like to ask if someone knows anything about how the large - 100Mvar/ 6kV - capacitor bank used for high power transformer load test can be protected. It is a special case where this bank is used only for 5-6 hours at a time and only few times a year. Maybe someone is working in...
Can anybody please help with some information about 400kVA Caterpillar Diesel generator with Perkins motor and ECM Perkins Governor.
I didn't find this information in the technical manual and unfortunately the respons of the distributor here(Eneria) is not as should be.
I want to know the value...
Dear All,
I have a problem related with power factor correction in an aluminum producing plant. It is supplied from 110kV network, 2 different supplies (equal supplies, 2 autotrafos 220kV/ 110kV). The rectifier transformers are supplied directly from 110kV, the scheme is with 48 pulses for each...
I need to find manufacturers for air core medium voltage harmonic filtering reactors.
Does anyone know such manufacturers preferably in Europe?
Thank you!
Pafi
Hello!
I need help from someone experienced with an application for merchandise lifting between different floors of a storage facility.
I am using an ACS 550 from ABB, motor power is 5.5kW and the inverter was chosen for heavy duty application. The motor has a built in electro-mechanical brake...
I am looking for a basic explanation related to the presence (and necessity of filtering) of the 3rd harmonic current in the secondary of an 25 MVA, 110/ 6kV, star/ delta, ungrounded secondary transformer.
This harmonic can be related to the presence of arc furnaces as a load and be of zero...
Trying to design a PFC bank for medium voltage application, 10kV system voltage and measuring the system harmonics, I found out that the even number harmonics are really big: 4,65% the second order current harmonic, 2% the 4-th and 1.25% 6-th harmonic. Also pretty big was the third and triplen...
I need some help in preparing my answer for one client who needs PFC for a 6kV network. I proposed an automatic bank but he asked me why not synchronous compensator. He has no synchronous motor installed, so if would be to choose this method he will have to buy one.
Maybe someone can explain...
Most of PFC regulators - all that I know - work on cos FI measurement (displacement PF). In a high harmonic content situation, the difference between cos FI and power factor PF is very big and depends on the value of THD. And the Utility Company meter measures PF, not cos FI. Does anybody know a...
I'm looking for information regarding reliability of the medium voltage vacuum contactors type JCZ5 produced by
GUOGUANG ELECTRIC CO., LTD. CHENGDU,from China.
They are really cheap, I just don't know how reliable they are, especially because I intend to use them in back to back automated...
