Recent content by Ali-rashid

It's crane winch.

We have two 30kw motors connected in parallel to a 75kw vfd. The motors are mechanically coipled to the load. In these cases, my knowledge says that the VFD can only work in V/F mode and vector control should not be used. But surprisingly, The VFD has only a vector mode and is set on Closed...

Hi we have a 20 tonnes crane run by a 60kw electric motor and its VFD. The dynamic braking resistor connected is 3.5ohm but we need to know the wattage of it and its model qnd brand is not clear. Is there a way to measure or calculate the wattage of the braking resistor?

Hi all. We have bought an AuCom MV softstarter panel and are arranging the delivery. We are already late in our project and need to do it by air, which needs the panel to be placed on its side horizentally. Some speciallists believe that doing so would damage the softstarter capacitors or other...

Thanks Che. Your comment along with some search got me the answer.

Hi All Can we use an earth leakage relay instead of an insulation monitoring device? Do they provide the same protection? Thanks

I was choosing contactors for DOL starting a 690v motor. I was reviewing the specs of Schneider LC1F400M7. It is written: 200kW on 400vAC. This means the rated current is about 400Amps on 400vAC. 280kW on 690vAC. This means the rated current is about 280Amps on 690vAC. Why the contactors is not...

Thanks every one. Your comments helped a lot understanding the scheme. I have one last question. Can R1 or R2 detect any ground faults on primary Delta windings or lines (the distance between CTs to Delta winding) considering that the primary is ungrounded?

The source is on the delta side. The problem is that my field experience was that the unbalance load cause the relays to see currents and operate depending on pickup value. I was wondering if existence of neutral wire and a grounded star would make a path for the unbalanced current to go out of...

I know ANSI46 can detect unbalance conditions very well but I am trying to understand the unbalance protections for a distribution transformer via 50N, 50G and 50GS. Our network uses delta/grounded wye transformers, so the protection scheme would be as below based on IEEE 242 book ...

Thanks Iran In case of protection relays for distribution in Iran usually Vamp, Micom, Fanox are used. But for Oil and Gas sector normally GE, Siemens and ABB are utilized. how does ZIV rank against these?

I have just heard of a brand for protection relays and comms solutions with name ZIV. I have not yet worked with their devices and don't know how is their quality. Is anybody familiar with them? How is their quality and level?

Hello all. I have some issues with PT wirings. your help is appreciated in advance. 1- can Wye PT wiring (3 PTs) provide phase angle measurements? 2- the figure below shows the connection of a single PT to Schneider Vamp40 feeder protection relay. the manual says that with this configuration...

We have a single phase motor. we also have a vfd which supports PSC( permanent splitted capacitor) and single phase Shaded pole motors. The pictures of the motor plate and the capacitor on it are attached. Is this motor categorized in any of the supported types, i.e. PSC or shaded pole? How can...

Hello I am struggling in finding the proper contactor for my requirement. I have an application which needs a contactor that satisfies the below characteristics: 690 Volt 1200 kW 1200 Amp please refer me to brands and models available in this range. please provide the exact model as I searched a...