Electrical Design for Fire Fighting Pumps




  
1- Fire Fighting System Equipment



The Fire Fighting System consists of many equipment as follows:

  1. Jockey pump,
  2. Electrical fire fighting pump,
  3. Diesel fire fighting pump,
  4. Electrical and control panels.

 
Video#1:Fire Fighting Pump Connection Details & Its Working Principles ( English).




1- Jockey pump
A jockey pump is a small pump connected to a fire sprinkler system to maintain pressure in the sprinkler pipes. This is to ensure that if a fire-sprinkler is activated, there will be a pressure drop, which will be sensed by the fire pumps automatic controller, which will cause the fire pump to start.

Video#2: Jockey pump brief (Arabic).




2-Electrical fire fighting pump
An electrical fire pump is a part of a fire fighting sprinkler system's water supply and powered by electric.


Video#3: electrical fire pump brief (Arabic).



 
3- Diesel fire fighting pump
An diesel fire pump is a part of a fire fighting sprinkler system's water supply and powered by diesel.

Video#4: diesel fire pump brief (Arabic).


 
4- Electrical and control panels
Electrical and control panels responsible for the electrical feeding and pump control.

Video#5: Electrical and control panels brief (Arabic).

 



  
1- Fire Fighting System Process


The fire fighting process is done by pumps designed specifically for the system.  Initially the jockey pump is used to maintain the pressure and when the fire is confirmed by a sprinklers or by the fire alarm panel the electric pump starts to work and then in case Failure or disconnection of Electricity for Electric Fire Pump The diesel pump is entered into the process.




3- Power Source(s) For Electrical Motor Driven Fire Pumps
According to NEC


  

Power Source(s) For Electrical Motor Driven Fire Pumps "NEC"


The mostly power sources used are:


A- Individual Source and Standby Generator

Individual Source and Standby Generator




B- Feeder Sources



Feeder Sources




4- Continuity of Power for Fire Pumps


to insure the continuity of power for fire pumps, the following notes must be taken into consideration:
  • Ground fault protection of equipment not permitted for fire pumps.
  • Direct Connection: The supply conductors shall directly connect the power source
  • permits, but does not require, the installation of a disconnecting means and associated over-current protection between a power source and the fire pump control devices




5- Over-current Device Selection 
  • Over-current protection must be set to carry indefinitely the sum of the locked rotor current of all fire and jockey pump motors plus all other load. 
  •  Locked‐rotor requirement applies only to the over-current device – not to the circuit conductors




Locked rotor currents can be found from the following Table







6- Conductor Selection 

  • The feeder conductors to the fire pump and associated equipment are required to have an ampacity not less than 125 percent of the full-load current (FLC) rating of the fire pump motor(s) and pressure maintenance pump motor(s), plus 100 percent of associated accessory equipment.
  • Starting. The voltage at the fire pump controller line terminals shall not drop more than 15 percent below normal (controller-rated voltage) under motor starting conditions. Exception: This limitation shall not apply for emergency run mechanical starting.
  • Running. The voltage at the motor terminals shall not drop more than 5 percent below the voltage rating of the motor when the motor is operating at 115 percent of the full load current rating of the motor.
  • Fire-rated cables will need to be specified if you’ll unable to bury the cables.






7- Example: "From NEC"












8- More Information 

 

  • Sizing recommendations for fire pump applications by cummins. click the Link 
  • Transformers shall be rated at a minimum of 125 percent of the sum of the fire pump motor(s) and pressure maintenance pump(s) motor loads, and 100 percent of the remaining load supplied by the transformer.
  • #1: To use individual sources it must be a reliable source. Reliable source definition at NFPA 20 as: 
      • Has not experienced any shutdowns of longer than 4 continuous hours in the year prior to plan submitter.
      • No power outages have been experienced in the area of the protected facility caused by failures in the power grid that were not due to natural disasters or electric grid management failure.
      • The normal source of power is not supplied by overhead conductors outside the protected facility.
      • Only the disconnect switches and over-current protection devices permitted are installed in the normal source of power. 
  • A separate electric utility service from a connection located ahead of (but not within) the service disconnecting means. Power sources [695.3]. 



9- Actual Data from site (Wiring Diagrams)

   Distribution of equipment in the room and connections between them

    
      wiring schematic diagram for control panel will have the following components:

  • IS1 : isolation switch 
  • SA1: Surge Arrester  3 phase  : The terms surge protection device (SPD) and transient voltage surge suppressor (TVSS) are used to describe electrical devices typically installed in power distribution panels, process control systems, for the purpose of protecting against electrical surges and spikes, including those caused by lightning.
  • CB1: circuit breaker 
  • CT1, CT2, CT3: current transformers 
  • SSS1: soft starter 
  • 1M : Contactor
  • CR4, CR5 : Power Relay


  

SSS1: soft starter



10- Room facilities Photos

 

Motor Base above water tank installation


turbine gearbox installation

Electrical Control Panel for diesel pump installation


zone control valve" back wire to fire alarm panel "


Sources:
NEC
NFPA
ecmweb.com


About the Authors:

Eng. Eman Mohamed https://www.linkedin.com/in/eman-mohamed-0459774a/
From Site:
Eng.Mohmaed abdala
Technician : Moamen Bakr

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