Main and standby switching method of fire pump
The main and standby switching methods of fire pumps mainly depend on the selection of the control signal source, usually including current signal control method and pressure signal control method. These two methods have their own characteristics and are suitable for different scenarios and needs.
1. Current signal control method
The current signal control method is a common method for main and standby switching of fire pumps in current fire protection design. Its working principle is as follows:
Working principle: The working status of the fire pump is judged by monitoring the motor current signal of the water pump. When the motor has abnormal conditions such as short circuit, power failure or excessive current, the system will automatically switch to the motor of another water pump unit, stop the work of the faulty pump, and start the standby pump.
Advantages: It can reflect the motor failure in time, because the motor failure is often the main failure of the water pump unit. In addition, this method is widely used in China and the technology is mature.
Note: Although the current signal control method can reflect the motor failure, it cannot directly indicate whether the fire pump actually discharges water. Therefore, in actual applications, it may be necessary to combine other monitoring methods to ensure the normal operation of the fire pump.
2. Pressure signal control method
The pressure signal control method realizes the switching of the main and standby pumps by setting an electric node pressure gauge on the water outlet main pipe. Its working principle is as follows:
Working principle: When the control box receives the start command, it will start any fire pump. If the pressure indicated by the electric node pressure gauge after working fails to reach the set pressure value, the control box will automatically switch to another pump and start its work.
Advantages: It can directly reflect the actual water discharge of the fire pump and provide a reliable way for the automatic control of the fire water supply system. In addition, this method has been widely used in foreign automatic sprinkler fire extinguishing systems.
Notes:
The electric node pressure gauge should be installed on the water outlet main of the fire pump to ensure accurate measurement of the water outlet pressure.
In the circuit design of signal control judgment, a certain time delay needs to be set to avoid mis-switching caused by pressure fluctuations.
The switching of the pressure signal control method can arbitrarily specify the main pump or standby pump of the fire pump, or it can be switched regularly to extend the service life of the equipment.
3. Summary
In practical applications, these two methods can be used in combination to improve the reliability and safety of the fire pump system. At the same time, no matter which method is used, it is necessary to ensure that the control of the fire pump should have the function of local control in addition to automatic control, so that manual operation can be performed in an emergency.
