75 KW MOTOR CONNECTED IN MCC THEN MCC INCOMER TRIPPED

What is JPF... ?

MCC trip on what?, Overcurrent, Earth Faults,...?

MCC incomer MCCB rated AMP...?

What is PCC...?

75KW motor starter with what starters? DOL or Star Delta...?.

Sorry, Can't answer this question. Information is not enough.

Please include more information. Whatever electrical system you have in your country are totally different with other country. No doubt the electrical operating principle are the same.

Question that you ask, are seem that you are not an Electrician people. Electrician will give the full information on the question ask.

JPF MEANS JET PULSE FILTER

MCC MEANS MOTOR CONTROL CENTRE

PCC MEANS POWER CONTROL CENTER

75 KW MOTOR IS CONNECTED WITH DOL STARTER.

FIRST WE ARE CONNECTED 75 KW MOTOR IN MCC WHILE STARTING MOTOR TAKES 900A(ITS FULL LOAD RATED IS 128A). THAT TIME FEEDER PROTECTION IS WITH THERMAL OVERLOAD RELAY. SO THAT IT IS TRIPPED AND NOT ONLY THAT FEEDER TOTAL THAT MCC INCOMER(RATED 800A) TRIPPED IN OVER CURRENT.

AFTER THAT WE ARE CONNECTED IN PCC WITH MM30 RELAY PROTECTION THEN MOTOR IS NOT TRIPPED.

THIS IS FULL INFORMATION.

IAM AN PURE ELECTRICAL PERSON I THINK ALL SHOULD UNDERSTAND SO THAT I WRITE IN THAT FORMATE(MCC ,PCC)..

U CAN KNOW MEANS TELL ME THE REASON.

In your MCC panel with the main MCCB of 800 A, what are the other load that is connected to this MCC panel other than the 75 KW motor.?

In your PCC panel, What is your Main MCCB rated Amps and when you connect this motor of 75KW to one of the sub MCCB, and what is the MCCB rated Amp?

We don't have the name of PCC. We call it Main Distribution Board "MSB" and all the other sub board getting supply from this MSB is call Sub Distribution Board or "Sub DB"

dear,

simply , there is no fault in the load side or electrical system.

mcc being a secondary equipment, after pcc , must be having low current incomer. it must be less then 900 amp. So, system tripped.

PCC being heavy , I assume, switch gear provided cope up the starting current , so, you observed zero tripping.

All you should take care while operating on mcc are

1. starting current of motor

2. starting time of motor to reach full speed.

in between, motor will draw more current. Switch gear should be such that there should not be tripping during the starting process of motor.

It's true. In order to solved and give you the correct answer to your motor tripping problem, we need to know the actual total load connected to your MCC panel. Since the MCC panel being a secondary equipment panel, I do believed that, there will be some other load connected to it. So finally, when you connect your 75KW motor to your MCC panel, you do not have the full capacity of 800A. It may be less that 700A or less than that and it all depend to the total load connected to your MCC panel.

For most of the MCCB like the 630A and above, there is a Current and TMS setting for the delay of tripping. Assuming, that if your MCC panel does not have any other load connected to it and only this 75KW motor, then, with DOL starter, it is possible to set the delay tripping time longer, since it will take about 2 to 2.5 sec to full run the motor.

Connected your motor to the PCC, like what Mr. Harry Potter had mention, "PCC being heavy , I assume, switch gear provided cope up the starting current , so, you observed zero tripping."

It may because your PCC is having a higher capacity of the MCCB like 1200Amp or 1500Amp MCCB. With this, hugh capacity, definitely the MCCB will not trip during you start your 75KW motor. The capacity is much higher than your MCC panel of 800Amp MCCB.

That why, we ask for your rated amp of your PCC MCCB. If your PCC panel rated as 800Amp I can gruantee that the tripping problem will still be the same as you connected to your MCC Panel.

Under the IEE regulation, motor of 13HP and above should be using Star Delta Starter. If you use star delta starter to start your 75 KW motor, it should not be a problme at your MCC panel as it takes only 1/3 of your motor starting current.

we are dividing the PCC & MCC on the power rating the motor or feeder having capacity of above 75KW will be connected to PCC and motor below the 75KW should be connected to MCC