The “Ultimate” Trip Setting

[xptpcrewx]

What exactly does “ultimate” trip setting mean with relation to section 430.226 and motor protection in general?

Ampere Rating & Interrupting Capacity for Motor Disconnect (Over 1000 Volts, Nominal)

Ampere Rating & Interrupting Capacity for Motor Disconnect (Over 1000 Volts, Nominal) Can someone tell me if/where the NEC has Ampere Rating & Interrupting Capacity requirements for disconnects on motors operating above 1kV nominal? Also, just to throw a wrench in the works, consider motors...

forums.mikeholt.com

I’ve seen this term used with older motor protection relays and literature, yet don’t really have any context about what it means.

 

[jim dungar]

Some protective relays especially MV, had multiple overcurrent trip/alarm points such as jam protection and stall, my guess is the ultimate trip is the overcurrent protection function equivalent to a typicall bimetal overload relay set to NEC maximum values.

 

[xptpcrewx]

my guess is the ultimate trip is the overcurrent protection function equivalent to a typicall bimetal overload relay set to NEC maximum values.

You might be onto something. I just found a datasheet on the following thermal overload device:

https://npeinc.com/manuals/Adobe%20E-Manuals/GE%20Relays/GEH-3243C%20CR224C,D,E%20and%20F%20Ac%20or%20DC%20Thermal%20Overload%20Relays.pdf

Under the Heater Selection section, it states, "The heaters will ultimately trip the relay in a 40 C ambient, on a current which is approximately the minimum value of motor full - load current listed in the table, multiplied by 1.25". So in this context, does this mean "ultimate" trip is nothing other than when the bimetal strip generates sufficient heat to deflect and cause the relay contacts to open? (basically what is now commonly called the pick-up setting of an overload relay).

What is throwing me off is when I come across this term, its with respect to solid-state or digital relays. Possible historic carryover of the word?

 

[jim dungar]

Yes, I am sure it is historic.

 

[xptpcrewx]

Yes, I am sure it is historic.

For those experienced with the NEC standards development process, do you think a PI submittal to change the word "ultimate" in favor of the more modern "trip or pick-up setting" would be rejected? What could the opposition look like?

 

[Hv&Lv]

What exactly does “ultimate” trip setting mean with relation to section 430.226 and motor protection in general?

Ampere Rating & Interrupting Capacity for Motor Disconnect (Over 1000 Volts, Nominal)

Ampere Rating & Interrupting Capacity for Motor Disconnect (Over 1000 Volts, Nominal) Can someone tell me if/where the NEC has Ampere Rating & Interrupting Capacity requirements for disconnects on motors operating above 1kV nominal? Also, just to throw a wrench in the works, consider motors...

forums.mikeholt.com

I’ve seen this term used with older motor protection relays and literature, yet don’t really have any context about what it means.

For those experienced with the NEC standards development process, do you think a PI submittal to change the word "ultimate" in favor of the more modern "trip or pick-up setting" would be rejected? What could the opposition look like?

I’m not experienced with NEC standards development but my belief is it will be denied.
One definition of “ultimate” is final.
with many of these CBs there is continuous current adjustments, long term delay, short term delay, ground, etc. all of these can be set differently.
your continuous can be set from 5-1000A (example numbers only) , 50p can be set to 5 or 10,000A, short term delay can be set to delay up to your 50 setting, and others anywhere in between.

What it’s saying is no matter what you set your breaker trip settings to, the settings can’t be more than 115% of the CONTROLLERS rating.