May I ask if it is possible to set up a interlock for the standby pump to start automatically in a centrifugal pump?
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The unit is equipped with two desalination water pumps, which are quite important; the shutdown of either one has a significant impact. It would be useful to install a backup pump along with a signal interlock system. The pumps are centrifugal pumps, and there is a concern that the high starting current when the outlet valve is open could damage the motor
Many of the centrifugal pumps I use in my installations come equipped with auto-start interlocks, which is normal; it’s possible to design the pump motors in such a way as to prevent excessive starting currents from causing damage……
Self-starting refers to the ability of a motor that is operating normally to start up again on its own once there is a sudden power outage or low voltage supply. The starting current of a motor is 4 to 7 times the rated current. If all the motors in a device are equipped with self-starting features, they will start simultaneously the moment power is restored after a power outage. The high starting currents exert significant stress on the transformer and the entire electrical network, causing fluctuations in the power supply network and leading to serious consequences. Therefore, when installing self-starting protection for motors, thorough calculations must be carried out, and such protection is only applied to a few critical devices.
Pump systems can be equipped with a function to start automatically at low flow rates or low pressures; when in standby mode, the switch should be set to automatic and both the inlet and outlet valves should be fully open. If the fluid being handled is relatively light, it is also advisable to keep the bypass valve for the pump’s outlet valve open to allow exhaust. Regarding the overcurrent that can occur due to high flow rates when starting the pump, I believe this should be taken into account during the design phase
It should be fine; don’t all lubrication pump systems start automatically? No problem
Sure, this is my compressor recirculation pump.
If it’s very important, then set a chain
The automatic start-up of important centrifugal pumps works fine (the power should not be too high; the motor should be a low-voltage 380V motor), but it is advisable to choose a motor with a higher capacity – the selection of the motor is based on calculations. Our system is equipped with two desalination water pumps, which are also centrifugal pumps; a standby pump is also set up to start automatically.
It’s possible, but keep in mind: 1. Traffic control should be set up from the back end； ⒉The power of the motor used should be slightly higher ； ⒊The inlet of the standby pump must be fully open.
Centrifugal pumps can be equipped with a standby pump auto-start interlock; it is sufficient to design the interlock control valve to open after the pump starts.
Both the deaeration water pump and the hot water pump in our system are equipped with automatic startup features when pressure drops, but we are also concerned that high current during startup could damage the motors, so we have not activated these features yet
A self-starting interlock can be set up; as long as the right motor is selected, there will be no problems
It might be okay to use a larger motor, but power consumption will definitely increase; it’s better to strengthen inspections. Our lubricating oil pump is a screw pump; is the one used on the fifth floor a centrifugal pump?
Yes, it’s better to choose a motor that is larger in size.
Our crude oil pumps, bottom of tower pumps, and fuel oil pumps can all start automatically after a delay following a trip
Do you mean that the outlet valve of the backup pump should remain open, with the check valve serving to prevent backflow? That should work; choose a motor with sufficient power. However, it’s not a big issue if it happens occasionally. Another option is to increase the time for circuit control and protection.
As long as your company’s power grid capacity and maximum current allow it, you can consider the automatic startup of critical equipment.
Many commonly used centrifugal pumps are equipped with self-starting switches, such as the pumps used in cooling tanks and those located in sludge tanks. These pumps have self-starting switches that allow them to start automatically once the liquid level reaches a set value; it is also necessary to keep the outlet valve open. Additionally, for example, in the case of auto-backwash filters used in hydrocracking processes, if there is a sludge tank associated with them, the pump located at the bottom of that sludge tank also has a self-starting switch. The pump will start automatically once the sludge discharged after backwashing enters the sludge tank and its level reaches the set value.