200A Breaker Tripping

[danilo]

Guys,

Appreciate your expertise on this problem.

Have this 200A main breaker with ten(10)-50A branch breakers that serve split type aircon units. This breaker always trips when 80% loaded.When i checked the voltage rating of breaker, i found out that its rated 115/230 v which i believe would not fit to our system of 1ph,230 volts ungrounded service.I guess had the breaker been rated 230v or 230/480v there would be no problem like this.

Kindly see if im right with this view.

thanks

Danilo

 

[catchtwentytwo]

Re: 200A Breaker Tripping

Danilo,

I don't think the voltage rating is the problem.

A typical "spec" breaker is a commodity item that doesn't have a 100% rating so the 80% loading might be on the "hairy edge" of tripping.

How long are you at 80% of the rating? Does the breaker have any trip adjustments? What is the ambient temperature where the panel is located? That could contribute to the tripping as well.

 

[charlie tuna]

Re: 200A Breaker Tripping

danilo,
how long has this breaker been exposed to 80 per cent load? you know that each time this breaker trips--it's trip setpoint is reduced somewhat? again, you are asking a question that has many answers. until you have the capability to know what is happening to the load side of this breaker when it trips -- you and we --can only guess at what the problem is? you power source could be causing it do to a "low voltage" condition which drives the current up beyound the trip setpoint of the breaker. you already asked about a problem with a 225 kva transformer without knowing what is happening inside the transformer. you or your company need to invest in a power recorder or rent one and monitor both of these problems to determine what is causing the problem. or hire a contractor who has the correct equipment. you don't want to guess at the solution to these problems-- a new 225kva transformer is expensive and if you changed the 100 amp breaker and it tripped the next day -- you would have only found out that "it wasn't the breaker"!!!

 

[catchtwentytwo]

Re: 200A Breaker Tripping

Danilo,

Charlie has some excellent points.

I suggest you go to Dranetz-BMI's Web Page web page and register for the free Web-Based Seminars. There are recorded ones for Power Quality Surveys and Harmonic Recording that you can take on your own schedule You can also sign up for future "live" sessions.

 

[senti7rs]

Re: 200A Breaker Tripping

You should check the full load amperage that each unit draws,then size your conductors,consider the lengh too,because of the voltage drop(more resistance,more current ,and more heat),then size your circuit protection,but don't leave it right on the border line of 80% go one size up without exceeding the ampacity of the conductors. make sure you calculate the length because resistance increases with length and motors will keep on pulling amps until they get the power they need. Check to make sure you have really good connections,plenty of copper under yor lugs or any connection ,more copper more current.make sure you are grounded.Make sure your 200a breaker isn't tied in to some kind of g.f.c.i or arc fault, those things are easy to trip.make sure everything else besides the electrical is doing fine too.I bet if you did these things you will solve your problem,maybe the tripping breaker is the semptom of a poorly installed electrical system. Feed back anyone.

 

[senti7rs]

Re: 200A Breaker Tripping

you can't run but 3 units at a time anyway if you've install everything right.10 times 50a is 500 AMP.50 times 3 is 150AMPS,hopefully there is nothing else in you panelboard because that is more current.if it's a feeder panel don't bond the neutral and ground together and don't drive another grounding electrode.

 

[peter d]

Re: 200A Breaker Tripping

Could the problem could be inrush current, assuming multiple units starting simultaneously?

 

[danilo]

Re: 200A Breaker Tripping

Dear All,

you really helped me a lot!appreciate it..

by the way, this 200A tripping is altogether different scenario from 225 drytype xformer..

the reason why i suspect the 115/230 v as the main culprit why this breaker keeps on tripping is because,as per code,using this breaker is not recommended for 230v ungrounded service.just wanna know why it said so when you view it differently..though my case is not supported with test equipment data,i supposed the reason why its not code recommended is,it really wont work that way..i guess your analysis maybe right if our system here is a grounded system but since its not,im more inclined now to follow its recommendation to use a 230v or 230v/460v rated breaker.