Type "D", thermo-magnetic breaker??
- Thread starter jkim780
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Re: Type "D", thermo-magnetic breaker??
Was he able to tell you that it is a UL489 listed device which is a stand alone OCPD or a supplementary protector, UL1077?
UL489 listed devices are tested to fall within a given thermal inverse time current curve. So to deviate from that would not qulify for a UL489 listing. There is no specific magnetic requirements that I'm aware as the manufacture sets the magnetic trip calibration to open within its KAIC rating to protect the breaker by clearing the fault while continuing to pass the strenuous UL testing requirements. The mangnetic calibration is commonly 10x the breaker rating +-20% and even more. Smaller breakers an be 6-7x the breaker rating.
UL1077 devices are supplementary protectors and are not to be applied as a substitute for a UL489 listed device.
The only thing that I can think of with reference to the 'D' is that supplementary protectors are commonly available with different thermal curves which may be what the 'D' stands for. I noticed that the C-H type WHS supplimentary protector has a 'B', 'C', and 'D' trip curve option.
Dave
Slow blow thermal or magnetic? Somehow that doesn't surprise methat "sales reps" not understand what they are selling as my the company that I worked for had plenty. They are similar to simple peddlers and weren't hired for their product knowledge. I have found that a good sales rep will know the technical aspects of the product he's representing and how it is applied or knowledge to help you apply it properly.
Was he able to tell you that it is a UL489 listed device which is a stand alone OCPD or a supplementary protector, UL1077?
UL489 listed devices are tested to fall within a given thermal inverse time current curve. So to deviate from that would not qulify for a UL489 listing. There is no specific magnetic requirements that I'm aware as the manufacture sets the magnetic trip calibration to open within its KAIC rating to protect the breaker by clearing the fault while continuing to pass the strenuous UL testing requirements. The mangnetic calibration is commonly 10x the breaker rating +-20% and even more. Smaller breakers an be 6-7x the breaker rating.
UL1077 devices are supplementary protectors and are not to be applied as a substitute for a UL489 listed device.
The only thing that I can think of with reference to the 'D' is that supplementary protectors are commonly available with different thermal curves which may be what the 'D' stands for. I noticed that the C-H type WHS supplimentary protector has a 'B', 'C', and 'D' trip curve option.
Dave
tony_psuee
Senior Member
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Re: Type "D", thermo-magnetic breaker??
Type "D" is most likely the trip curve of the circuit breaker. What is the load you are planning on protecting? That should help you determine the proper trip curve of the circuit breaker. As templdl indicated, it would be important to know the how the device is listed of UL1077 or UL489 to determine if branch circuit protection is also required.
Tony
Type "D" is most likely the trip curve of the circuit breaker. What is the load you are planning on protecting? That should help you determine the proper trip curve of the circuit breaker. As templdl indicated, it would be important to know the how the device is listed of UL1077 or UL489 to determine if branch circuit protection is also required.
Tony
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- Wisconsin
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- PE (Retired) - Power Systems
Re: Type "D", thermo-magnetic breaker??
Most of the small supplementary/miniature breakers (35mm DIN rail mounted style) are available with different trip characteristics. There is no standard for the exact trip times. Nor is there any standard designation, one manufacturer might call it a class D curve and another might call the same thing a type K curve.
The common curves are:
slow trip at about 10-14 times FLA, used with high inrush, circuits like solenoids and transformers
normal trip at about 7-10 times FLA
fast trip at about 3-6 times FLA, used primarily with sensitive circuits
Most of the small supplementary/miniature breakers (35mm DIN rail mounted style) are available with different trip characteristics. There is no standard for the exact trip times. Nor is there any standard designation, one manufacturer might call it a class D curve and another might call the same thing a type K curve.
The common curves are:
slow trip at about 10-14 times FLA, used with high inrush, circuits like solenoids and transformers
normal trip at about 7-10 times FLA
fast trip at about 3-6 times FLA, used primarily with sensitive circuits
Re: Type "D", thermo-magnetic breaker??
Jim Dungars right on the mark and Dave and Tony are right that this isn't an American standard. It's a European standard for ordinary circuit breakers. I don't think it has any significance for the North American market.
Like Jim writes, the standard for the trip time is unexacting. The different instantaneous trips are:
D: 10-?? X, Typically 10-14 X
C: 5-10 X, Typically 5-7 X
B: 3-5 X, Typically 3-5 X
Type D for transformers and motors, Type C is common for general purpose use, Type B is for residential. You could say that types D and C are slow blow and type B is fast acting, but keep in mind it isn't a fuse.
{Edited for poor spelling and grammar}
[ January 26, 2005, 10:19 AM: Message edited by: c-h ]
Jim Dungars right on the mark and Dave and Tony are right that this isn't an American standard. It's a European standard for ordinary circuit breakers. I don't think it has any significance for the North American market.
Like Jim writes, the standard for the trip time is unexacting. The different instantaneous trips are:
D: 10-?? X, Typically 10-14 X
C: 5-10 X, Typically 5-7 X
B: 3-5 X, Typically 3-5 X
Type D for transformers and motors, Type C is common for general purpose use, Type B is for residential. You could say that types D and C are slow blow and type B is fast acting, but keep in mind it isn't a fuse.
{Edited for poor spelling and grammar}
[ January 26, 2005, 10:19 AM: Message edited by: c-h ]
ron
Senior Member
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- New York, 40.7514,-73.9925
Re: Type "D", thermo-magnetic breaker??
As a side note, what do you think about a high magnetic withstand of 20 x trip for a breaker sold in the US.
I use them all the time for the right application. Cool.
http://www.squared.com/us/products/circuit_breakers.nsf/unid/1E49571E7E13ED8585256D73005AEADF/$file/lacbFrameset.htm
As a side note, what do you think about a high magnetic withstand of 20 x trip for a breaker sold in the US.
I use them all the time for the right application. Cool.
http://www.squared.com/us/products/circuit_breakers.nsf/unid/1E49571E7E13ED8585256D73005AEADF/$file/lacbFrameset.htm
Re: Type "D", thermo-magnetic breaker??
Thanks for the reply. I am always learning new info. from you guys. I think you are right. It seems he is talking about miniature breaker with type D trip curve. But I don't think he knows the difference between UL 489 & UL1077.
My load is a "Ultra Violet System" on Swimming pool. 480V, 3Ph, 60Hz, 5Kw. They are asking for a 32Amp rating, Type "D" thermo-magnetic internal circuit breaker as well as external.
I think I can give them a miniature breaker with D trip curve for internal cb comply with UL1077 but the external cb wil have to be UL489 complied for brach circut protection.
Then my next question is
1) Can I use this miniature cb with typical molded circuit breaker, like HACR type? (MCCB trip at about 5-10x of the rating and type D trips at 10-14x. MCCB will always trip first before type D).
or should I use high magnetic withstand cb like ron suggested?
2) How does this slow trip cb protect the sensitive load?
3) Ron, when you use this "high magnetic withstand cb", do you always perform the selective coordination?
Thanks.
[ January 26, 2005, 10:52 AM: Message edited by: jkim780 ]
Thanks for the reply. I am always learning new info. from you guys. I think you are right. It seems he is talking about miniature breaker with type D trip curve. But I don't think he knows the difference between UL 489 & UL1077.
Ron,
My load is a "Ultra Violet System" on Swimming pool. 480V, 3Ph, 60Hz, 5Kw. They are asking for a 32Amp rating, Type "D" thermo-magnetic internal circuit breaker as well as external.
I think I can give them a miniature breaker with D trip curve for internal cb comply with UL1077 but the external cb wil have to be UL489 complied for brach circut protection.
Then my next question is
1) Can I use this miniature cb with typical molded circuit breaker, like HACR type? (MCCB trip at about 5-10x of the rating and type D trips at 10-14x. MCCB will always trip first before type D).
or should I use high magnetic withstand cb like ron suggested?
2) How does this slow trip cb protect the sensitive load?
3) Ron, when you use this "high magnetic withstand cb", do you always perform the selective coordination?
Thanks.
[ January 26, 2005, 10:52 AM: Message edited by: jkim780 ]
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: Type "D", thermo-magnetic breaker??
UL489 and UL1077 are not issues when discussing the different trip times of breakers.
Square D does make a 240V UL489 miniature breaker with non-standard trip ratings and with what they call C and D trip curves. They also make a similar looking 240V and 480V UL1077 supplementary breaker. For more information on UL489 vs UL1077 see pages 4 and 5 of Square D promotional publication 0600BR0101.
And remember the trip curves have no inter-company meaning. Square D has B, C, and D while ABB offers B, C, K, and adds Z for very sensitive applications.
UL489 and UL1077 are not issues when discussing the different trip times of breakers.
Square D does make a 240V UL489 miniature breaker with non-standard trip ratings and with what they call C and D trip curves. They also make a similar looking 240V and 480V UL1077 supplementary breaker. For more information on UL489 vs UL1077 see pages 4 and 5 of Square D promotional publication 0600BR0101.
And remember the trip curves have no inter-company meaning. Square D has B, C, and D while ABB offers B, C, K, and adds Z for very sensitive applications.
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