Inverse time breaker vs instantaneous

[Jpflex]

I have a 5 hp motor, 230, 460, 190 and 360 volt options, 3 phase, nameplate full load amps ranges confusingly listed at 12 & 3/6, 17, 9.55, and 4.78, service factor 1.15, continuous duty, efficiency at 88.5%, power factor 85%, design B, RPM 3520

System runs 440 volt 3 phase


Wire

NEC code chart 7.6 Full Load Current amperes x 1.25% = wire good to 9.5 amperes after derating or minimum code 14 AWG wire

Overload protection

I chose smallest full load ampere rating on motor name plate 4.78 i amperes x 1.25% = 5.97 amperes so if this is max I cannot go over this or go next size up to 6 amperes if heater on NEMA starter is not standard?

Overcurrent protection

7.6 FLC x 800% if using instantaneous breakers 60.8 I amperes max or 19 i amperes if using inverse time breakers

This pictured breaker may be too small if it were an instantaneous breaker BUT HOW DO I KNOW IF THIS WERE AN INSTANTANEILOUS OR INVERSE BREAKER?

Or if the breaker does not clearly label if it’s inverse or instantaneous how do I determine this?

 

[don_resqcapt19]

Need a picture of the nameplate as the 12 and 17 numbers don't make any sense. It seems that the 3/6 are the 460/230 volt currents, and the 4.78/9.55 are the 380/190 volt currents.

You use the current that applies to the supplied voltage for the selection of the overload setting.

Instantaneous trip breakers can only be used as part of a listed combination motor starter.

The breaker in the picture would be an inverse time thermal magnetic breaker. As far as finding out what the breaker is, you look it up. It is a GE TEY breaker. That breaker can only be used on a wye power source as it is a slash rated breaker.

 

[augie47]

Instantaneous breaker can only be used as part of a factory assembly
The picture you show is a type TEY, a inverse time breaker

opps..don covered it

 

[Jraef]

Overload protection

I chose smallest full load ampere rating on motor name plate 4.78 i amperes x 1.25% = 5.97 amperes so if this is max I cannot go over this or go next size up to 6 amperes if heater on NEMA starter is not standard?

Where are you coming up with the 1.25 (which is I think what you meant, not 1.25%)? Article 430.32(B)? If so, you are misinterpreting it (as so many people do). That is a generalized statement as it applies to the EFFECT of a separate OL device. How you GET THERE is a different story and is covered in 110.3(B); equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

You have to follow the instructions from the manufacturer of the overload relay as to how to select the heaters or setting. Some (many) of them ALREADY factor in the 125% pick-up point into the OL relay itself, so they will tell you to use the motor nameplate FLA directly, no multipliers. Some factor in 115% already, then tell you to add another 10% if the motor has a 1.15SF. If you automatically just put 125% on your sizing without checking, to a relay in which THEY already had the 125% applied, you now have 156% of motor FLA before the OL relay even BEGINS to start the tripping process, so you can lose the motor. As an example, if the motor drew 150% current, a basic I²t OL relay should trip in around 4 minutes. But with the doubled up 125% issue, it NEVER trips.

This practice of automatically adding the 1.25 multiplier is what keeps motor rewind shops in business... As I said, LOTS of people do this because they were taught to, but by people that were ALSO doing it wrong!

 

[Jpflex]

Where are you coming up with the 1.25 (which is I think what you meant, not 1.25%)? Article 430.32(B)? If so, you are misinterpreting it (as so many people do). That is a generalized statement as it applies to the EFFECT of a separate OL device. How you GET THERE is a different story and is covered in 110.3(B); equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

You have to follow the instructions from the manufacturer of the overload relay as to how to select the heaters or setting. Some (many) of them ALREADY factor in the 125% pick-up point into the OL relay itself, so they will tell you to use the motor nameplate FLA directly, no multipliers. Some factor in 115% already, then tell you to add another 10% if the motor has a 1.15SF. If you automatically just put 125% on your sizing without checking, to a relay in which THEY already had the 125% applied, you now have 156% of motor FLA before the OL relay even BEGINS to start the tripping process, so you can lose the motor. As an example, if the motor drew 150% current, a basic I²t OL relay should trip in around 4 minutes. But with the doubled up 125% issue, it NEVER trips.

This practice of automatically adding the 1.25 multiplier is what keeps motor rewind shops in business... As I said, LOTS of people do this because they were taught to, but by people that were ALSO doing it wrong!

Yes i came across an old catalog with heaters for starters and some included the 1.25 multiplier which you questioned how I got in original post.

However, the company I work for will not buy new heaters or starters from catalogues because they apparently don’t like spending the millions of dollars of invester money they receive for work related causes. Instead the owner goes to junk piles or auctions for random and out dated electrical supplies which often don’t match the application or project being done. We have some old junk piles with breakers and old hammar contact starters, pneumatic time delay relays mostly rusted and all without a way to determine the size of heaters already on the starters

There is another combination type starter with over current protection and overload protection adjustable by a rotating flat head screwdriver knob but often the overcurrent side is way out of scale

 

[Jpflex]

Instantaneous breaker can only be used as part of a factory assembly
The picture you show is a type TEY, a inverse time breaker

opps..don covered it

How can you tell the difference?

 

[Jpflex]

Need a picture of the nameplate as the 12 and 17 numbers don't make any sense. It seems that the 3/6 are the 460/230 volt currents, and the 4.78/9.55 are the 380/190 volt currents.

You use the current that applies to the supplied voltage for the selection of the overload setting.

Instantaneous trip breakers can only be used as part of a listed combination motor starter.

The breaker in the picture would be an inverse time thermal magnetic breaker. As far as finding out what the breaker is, you look it up. It is a GE TEY breaker. That breaker can only be used on a wye power source as it is a slash rated breaker.

There’s no part number to look this up or go online for details. Couldn’t a delta power source also provide slash or two voltage ranges when a neutral is derived from the tap middle of secondary b phase or stinger but using only phase to neutral such as 120 volts not 208 stinger

 

[augie47]

How can you tell the difference?

In your case the catalog number shown in your picture but as you already noted, instantaneous breakers are a lot higher ampere rating so that's another clue..

 

[Jraef]

How can you tell the difference?

Instantaneous-only breakers will have a very specific name / reference on them, like "MCP" (Motor Circuit Protector), which was the original from Westinghouse, or now Eaton calls them "HMCP" (because the trade mark on MCP expired); Square D calls them "Mag-Gard" because they are magnetic-only (same as instantaneous only); GE calls them "Mag-Break" for the same reason; Siemens / ITE calls them "E-TI" breakers and they say "Instantaneous Adjustable Trip" on the front.

The thing is, it still comes back to what Don said already; you cannot use instantaneous-only breakers in the field, other than EXACT 1:1 replacement of existing, there is no valid use for them outside of a MANUFACTURER of motor starters in a factory assembled and listed unit. So you should not really run into many situations where you have to be able to tell the difference. If you have to replace one, you can ONLY replace it with the exact same unit you removed.

 

[Jraef]

Couldn’t a delta power source also provide slash or two voltage ranges when a neutral is derived from the tap middle of secondary b phase or stinger but using only phase to neutral such as 120 volts not 208 stinger

While technically true of a 240V delta 3 phase 4 wire system, ONE of those phases will be 208V reference to ground, so a 3 pole 240/120V slash rated breaker would not be acceptable (and there is no "240/208V" slash rated breaker). If you were using a 2 pole breaker and ONLY connecting to A and C, phases, you could use a slash rated breaker, many panel systems will allow you to do that.

If you happened to stumble across one of the RARE 480/240V 3 phase 4 wire delta systems, the B phase to ground reference would be 277V and a 480/277V slash rated breaker would be fine. So the problem is really just that MOST delta systems you will come across in real life will be such that you CANNOT use a slash rated 3 pole breaker.

 

[kwired]

While technically true of a 240V delta 3 phase 4 wire system, ONE of those phases will be 208V reference to ground, so a 3 pole 240/120V slash rated breaker would not be acceptable (and there is no "240/208V" slash rated breaker). If you were using a 2 pole breaker and ONLY connecting to A and C, phases, you could use a slash rated breaker, many panel systems will allow you to do that.

If you happened to stumble across one of the RARE 480/240V 3 phase 4 wire delta systems, the B phase to ground reference would be 277V and a 480/277V slash rated breaker would be fine. So the problem is really just that MOST delta systems you will come across in real life will be such that you CANNOT use a slash rated 3 pole breaker.

480/240 three phase 4 wire delta isn't all that rare around here. And the B phase isn't 277 volts to ground it is 415 volts to ground. A 277/480 rated breaker can't be used on this system.

 

[jim dungar]

There’s no part number to look this up or go online for details.

Your picture clearly says it is GE type TEY, look just above the 480/277V marking.

 

[Tulsa Electrician]

While your reading on the subject.
Have a look at 250.122 D (2).

 

[don_resqcapt19]

There’s no part number to look this up or go online for details. Couldn’t a delta power source also provide slash or two voltage ranges when a neutral is derived from the tap middle of secondary b phase or stinger but using only phase to neutral such as 120 volts not 208 stinger

There is enough information to find a part number, but "TEY" is all you need to know to find out what type of breaker it is. You can find some info here. Note that the breaker has an AIC of 14kA which might be low in an industrial setting.

15-100A
Thermal Magnetic Trip
Type TEY/TEYF
Noninterchangeable Trip
Bolt-on
480Y/277V Class
TEY and TEYF breakers are one-inch wide per pole, compact, bolt-on circuit breakers for use on grounded 480Y/277 Vac systems. Short circuit ratings at that voltage for TEY and TEYF are 14 and 18kA, respectively. TEYF also offers higher selectivity ratings with upstream devices (See DET-537 for details). The bolt-on mounting base (TEY3B) shown on page 3-116 makes TEY and TEYF suitable for various lug-lug applications.

 

[ptonsparky]

Some of the instantaneous breakers I've seen were odd amperages like, 4 or 7, for small motors. Those are two that stood out vs the multiple of 5 or 25 for time delays.

 

[jim dungar]

Some of the instantaneous breakers I've seen were odd amperages like, 4 or 7, for small motors. Those are two that stood out vs the multiple of 5 or 25 for time delays.

They are similar to fuses in that regard, however above 15A they are the more common ratings.

Decades ago the rules for instantaneous trip breakers were quite more relaxed than what we have today. At one point you could even get Mag-gard breakers in I-Line construction.

 

[Jpflex]

Instantaneous-only breakers will have a very specific name / reference on them, like "MCP" (Motor Circuit Protector), which was the original from Westinghouse, or now Eaton calls them "HMCP" (because the trade mark on MCP expired); Square D calls them "Mag-Gard" because they are magnetic-only (same as instantaneous only); GE calls them "Mag-Break" for the same reason; Siemens / ITE calls them "E-TI" breakers and they say "Instantaneous Adjustable Trip" on the front.

The thing is, it still comes back to what Don said already; you cannot use instantaneous-only breakers in the field, other than EXACT 1:1 replacement of existing, there is no valid use for them outside of a MANUFACTURER of motor starters in a factory assembled and listed unit. So you should not really run into many situations where you have to be able to tell the difference. If you have to replace one, you can ONLY replace it with the exact same unit you removed.

But I often have to sort out from a pile of 80s and 90s equipment so some of these components were in operation before I was in the field

 

[Joethemechanic]

480/240 three phase 4 wire delta

Never have seen that one. What is the typical application for the 240 single phase it supplies? If you need 120 you are going to need another transformer anyway. Or is it just a way to avoid corner grounding?

 

[Jpflex]

I noticed on a starter for a motor, another employee wired the load side of coil contact jumper to line 2 as normal and start button signal to its line side of coil as normal but he also jumped the load side (neutral) of the coil which has L2 “B” phase line potential to cabinet ground

This would put the cabinet at L2 potential similar to how a corner delta grounded transformer puts the cabinet to corner line potential. I know he messed up on this one

 

[Joethemechanic]

I noticed on a starter for a motor, another employee wired the load side of coil contact jumper to line 2 as normal and start button signal to its line side of coil as normal but he also jumped the load side (neutral) of the coil which has L2 “B” phase line potential to cabinet ground

This would put the cabinet at L2 potential similar to how a corner delta grounded transformer puts the cabinet to corner line potential. I know he messed up on this one

Sounds like he didn't have the right coil voltage, or didn't have a control transformer, and didn't have a neutral conductor. So he bootlegged a neutral from a ground