Sizing of Fire pump's Circuit Breaker according to NEC

[Bindim]

It is an exclusive electrical system for the fire-fighting pump.

The 13.8kV transmission line is an aerial type and is exclusive to the customer.

The transformer will be installed next to the fire fighting pump house.

There will be no other electrical system in this area than the exclusive fire fighting system.

We are in Brazil, but our client requires compliance with NFPA 20.

We are preparing the electrical project and the complete specification of the electrical panel that will perform the activation of the fire-fighting pump.
I have no doubt about the current value of the circuit breaker and its functions.

Our question is in the specific point of NFPA 20 about the circuit breaker, that is, should the FRAME of the circuit breaker support the blocked rotor current or only the circuit breaker current sensor?

Example:
Circuit breaker (Compact NSX100 model with only MA Unit Trip - Schneider): Has Frame In 100A and Magnetic Unit Pickup (Im) = 9 to 14 * In

 

[kwired]

This is our design (see attached file).
The electrical system is only for the fire pump and jockey pumps.
All componnents will be installed in a exclusive fire pump house.

As NFPA 20:2019
10.4.3.3.1 The circuit breaker shall have the following electrical characteristics:
(1) A continuous current rating not less than 115 percent of the rated full-load current of the motor
(2) Overcurrent-sensing elements of the nonthermal type
(3) Instantaneous short-circuit overcurrent protection
(4)* An adequate interrupting rating to provide the suitability rating of the controller discussed in 10.1.2.2
(5) Capability of allowing normal and emergency starting and running of the motor without tripping (see 10.5.3.2)
(6) An instantaneous trip setting of not more than 20 times the full-load current

Our question is in the specific point of NFPA 20 about the circuit breaker, that is, should the FRAME of the circuit breaker support the blocked rotor current or only the circuit breaker current sensor?

Per what you posted earlier I'd say it must have a continuous current rating not less than 115% full load current of motor. This basically is the switching rating not any trip rating/setting.

 

[Bindim]

I highlight the following points of attention of NFPA 20: 2019, in relation to the circuit breaker:

9.2.3.4 Where the overcurrent protection permitted by 9.2.3 is installed, the overcurrent protection device shall be rated to carry indefinitely the sum of the locked rotor current of the largest pump motor and the full-load current of all of the other pump motors and accessory equipment.

[My comment: This item 9.2.3.4 is applied to the external protection / circuit breaker and upstream of the Fire Pump Control Panel. In my specific case, I don't have this circuit breaker, so I have to dimension the protection fuse upstream of the transformer.]

10.4.3.3.1 The circuit breaker shall have the following electrical characteristics:
(1) A continuous current rating not less than 115 percent of the rated full-load current of the engine
(2) Overcurrent-sensing elements of the nonthermal type
(3) Instantaneous short-circuit overcurrent protection
(4) * An adequate interrupting rating to provide the suitability rating of the controller discussed in 10.1.2.2
(5) Capability of allowing normal and emergency starting and running of the motor without tripping (see 10.5.3.2)
(6) An instantaneous trip setting of not more than 20 times the full-load current

[My comment: This item 10.4.3.3.1 deals with the circuit breaker / protection internal to the Fire Pump Control Panel. It informs that it should not have thermal protection and that it should allow the motor to start in normal and emergency conditions and that the circuit breaker cannot have an instantaneous trip adjustment above 20 times the rated motor current. This item does not prompt "to carry indefinitely the sum of the locked rotor current".]

10.4.4 Locked Rotor Overcurrent Protection. The only other overcurrent protective device that shall be required and permitted between the isolating switch and the fire pump motor shall be located within the fire pump controller and shall possess the following characteristics:
(1) For a squirrel-cage or wound-rotor induction motor, the device shall be of the time-delay type having tripping times as follows:
(a) Between 8 seconds and 20 seconds at locked rotor current
(b) Three minutes at a minimum of 300 percent of full-load current engine

[My comment: This item 10.4.4 informs that the protection device, in the specific case the circuit breaker, must be of the time-delay trip type, do not trip for 8 to 20 seconds RLC and do not trip for 3 minutes with at least 3x FLA of the electric motor.]

Please comment and correct me where necessary.

 

[Bindim]

Per what you posted earlier I'd say it must have a continuous current rating not less than 115% full load current of motor. This basically is the switching rating not any trip rating/setting.

your
Thanks for your help.
How do you interpret items 10.4.3.3.1 and 10.4.4 (b) Three minutes at a minimum of 300 percent of full-load current engine?