Hi my name is wayne I have my own electrical contracting business and I have a question about 400 hz hook up. I was told my another electrician that it has been done in the past that electrical contractors have used 3 phase 120/208 panels for 400 hz but they needed to be bolt in breakers because of the heat. I have another person telling me that it is ok to use 3 phase 120/208 snap in breakers in a panel for 400 hz can I or is this a safety issue and why I would like technical info to pass on to the costomer. I was told to use bolt in breakers knowing that they are not rated for 400 hz but have been used in the past in this application. any info on this matter would be greatly appreciated. Thanks
400 hz
- Thread starter ace0912
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charlie
Senior Member
- Location
- Indianapolis
Re: 400 hz
In the UL White Book, you will find this title, CIRCUIT BREAKERS, MOLDED-CASE AND CIRCUIT BREAKER ENCLOSURES (DIVC). You will also find the following:
"RATINGS
Listed circuit breakers are rated 600 V or less. A circuit breaker is marked AC or DC or both AC and DC. A symbol (~), where used, represents AC. The frequency is included if other than 60 Hz.
Circuit breakers that have an interrupting rating higher than 5000 A are marked to indicate the higher rating(s).
An interrupting rating on a circuit breaker included in a piece of equipment does not automatically qualify the equipment in which the circuit breaker is installed for use on circuits with higher available currents than the rating of the equipment itself.
Circuit breaker enclosures that have a short circuit current rating are marked accordingly."
The bottom line is that the equipment must be listed for the use. It is time to check with the manufacturer's rep and not just pick up something at the counter. This is going to be a special order.
In the UL White Book, you will find this title, CIRCUIT BREAKERS, MOLDED-CASE AND CIRCUIT BREAKER ENCLOSURES (DIVC). You will also find the following:
"RATINGS
Listed circuit breakers are rated 600 V or less. A circuit breaker is marked AC or DC or both AC and DC. A symbol (~), where used, represents AC. The frequency is included if other than 60 Hz.
Circuit breakers that have an interrupting rating higher than 5000 A are marked to indicate the higher rating(s).
An interrupting rating on a circuit breaker included in a piece of equipment does not automatically qualify the equipment in which the circuit breaker is installed for use on circuits with higher available currents than the rating of the equipment itself.
Circuit breaker enclosures that have a short circuit current rating are marked accordingly."
The bottom line is that the equipment must be listed for the use. It is time to check with the manufacturer's rep and not just pick up something at the counter. This is going to be a special order.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Re: 400 hz
I have a chart from Square D that shows the effect of increased frequency on some of their circuit breakers.
The increased frequency results in the thermal side of a typical breaker as reducing its capacity (its also different for each style breaker and some do not even go up to 400 hz on the chart). For instance, a KA breaker is only good for 92% of its rated thermal trip point at 400 Hz.
The magnetic trip point goes the other way though. The same KA breaker takes 2.6 times the instantaneous current to trip at 400 hz versus 60 Hz.
They also point out the interrupting rating at 400 Hz is about 10% of what it is at 60 Hz.
Thats why I use fuses for these frequncy ranges.
I have a chart from Square D that shows the effect of increased frequency on some of their circuit breakers.
The increased frequency results in the thermal side of a typical breaker as reducing its capacity (its also different for each style breaker and some do not even go up to 400 hz on the chart). For instance, a KA breaker is only good for 92% of its rated thermal trip point at 400 Hz.
The magnetic trip point goes the other way though. The same KA breaker takes 2.6 times the instantaneous current to trip at 400 hz versus 60 Hz.
They also point out the interrupting rating at 400 Hz is about 10% of what it is at 60 Hz.
Thats why I use fuses for these frequncy ranges.
Re: 400 hz
Yes, some serious technical discussion with a knowledgeable manufacturer is in order. But 400Hz is not uncommon. 400HZ 208/120Y systems are frequently used in aircraft manufacturing.
There is increased impedance at the higher frequency, so keep an open mind to non-ferrous raceways (aluminum conduit), smaller conductors in parallel, (to lessen skin effect), etc.
Yes, some serious technical discussion with a knowledgeable manufacturer is in order. But 400Hz is not uncommon. 400HZ 208/120Y systems are frequently used in aircraft manufacturing.
There is increased impedance at the higher frequency, so keep an open mind to non-ferrous raceways (aluminum conduit), smaller conductors in parallel, (to lessen skin effect), etc.
Re: 400 hz
Square D has a bulletin posted on their website regarding the use of breakers at 400-hz. The bulletin number is 0100DB0101. It states that circuit breakers must be derated to 92% for non-continuous loads and derated twice (92% and 80%) for continuous loads.
Square D has a bulletin posted on their website regarding the use of breakers at 400-hz. The bulletin number is 0100DB0101. It states that circuit breakers must be derated to 92% for non-continuous loads and derated twice (92% and 80%) for continuous loads.
charlie
Senior Member
- Location
- Indianapolis
Re: 400 hz
From the Square D Data Bulletin, this is on page 2, "When applied at ambient temperatures other than 40?C, at frequencies other than 60 Hz, on dc systems, or in other extreme conditions, the performance characteristics of the circuit breaker may be affected. In these cases, the current carrying capacity and/or trip characteristics of the circuit breaker may vary. This bulletin explains how to correctly apply circuit breakers under these special conditions." The link is to the bulletin referred to in the above post.
From the Square D Data Bulletin, this is on page 2, "When applied at ambient temperatures other than 40?C, at frequencies other than 60 Hz, on dc systems, or in other extreme conditions, the performance characteristics of the circuit breaker may be affected. In these cases, the current carrying capacity and/or trip characteristics of the circuit breaker may vary. This bulletin explains how to correctly apply circuit breakers under these special conditions." The link is to the bulletin referred to in the above post.
jjhoward
Senior Member
- Location
- Northern NJ
- Occupation
- Owner TJ Electric
Re: 400 hz
My first exposure to 400hz was with some ECs who worked over the weekend at our lab facility. They brought 400HZ power to a few lines to our lab for an aircraft simluator. The lab was secure since this was classified military work (the ECs could not get into lab over the weekend). When we came into the lab on Monday we had about $10K worth of cooked digital equipment. They had applied the 440V/400HZ power to some lines that had been in use for 120V stuff. Everything smelled funny, lots of melted things, we couldn't believe it. We were lucky the place didn't burn down. Lots of coulombs at 440V/400Hz.
My first exposure to 400hz was with some ECs who worked over the weekend at our lab facility. They brought 400HZ power to a few lines to our lab for an aircraft simluator. The lab was secure since this was classified military work (the ECs could not get into lab over the weekend). When we came into the lab on Monday we had about $10K worth of cooked digital equipment. They had applied the 440V/400HZ power to some lines that had been in use for 120V stuff. Everything smelled funny, lots of melted things, we couldn't believe it. We were lucky the place didn't burn down. Lots of coulombs at 440V/400Hz.
tx2step
Senior Member
- Location
- North Texas, DFW area
Re: 400 hz
Most manufacturers can give you the ratings of their equipment at 400 HZ. Get it from them or you are just guessing, which will just lead you to problems.
My experience with 400 HZ is from contracting on military work. We never used ferrous boxes or conduit or fittings. Steel or iron will heat up.
Everything had to be aluminum or plastic.
Most manufacturers can give you the ratings of their equipment at 400 HZ. Get it from them or you are just guessing, which will just lead you to problems.
My experience with 400 HZ is from contracting on military work. We never used ferrous boxes or conduit or fittings. Steel or iron will heat up.
Everything had to be aluminum or plastic.
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