Hi MatthewDB
That is very helpful - highly appreciated. There are so many engineers, companies and panel manufacturers who use wound primary CTs for smaller motors - less than 45Kw. an 30Kw. almost in all cases such CTs are used for metering purposes. Operations crew always like to confirm that...
Thanks Scott UK
Thanks for the suggestion of using CTS with low secondary winding ratio to help register low currents. I was thinking in the direction of changing the ratio by increasing the primary winding from one to two or three. Can both options meet the same objective???
Hi jraef. Once again thanks for the response.
Are you saying you have never seen primary wound CTs used in DOL starters with characteristics I explained? A lot of panel manufacturers on my side of the woods use them. It means that there has been a general industrial misapplication that require...
Thanks a lot Waross for the response and advice.
You are right - it has been noticed that the the CT gave-in due to insulation failure caused by repetitive heating. It is likely that the CT burnt and broke the line. Then the motor single phased. This theory holds as pump had no blockage...
Hi jraef
Thanks for the question. Today we spend the day in an investigation, and it was agreed that the CB, O/L relay and the contactor were properly sized. However, the CT was determined to be the root cause of the incident. Although the current ratio was correctly specified, the fault...
I am an Electrical Engineers in a flammable material processing plant and I kindly need assistance from the forum regarding two fires we had in Motor Control Centers (MCCs).
In the last three months we have had two fires incidences in two different MCC’s, both originated from primary wound...
