Why does the variable frequency constant pressure water supply system trip frequently?

  Air switches, also known as circuit breakers, are commonly used low-voltage electrical protection devices that provide protection against overloads and short circuits. Leakage switches, also known as residual current circuit breakers (RCCBs), primarily protect against electrical leakage and electric shock.

      In a variable frequency constant pressure water supply system, we encountered this problem: the air switch (or leakage switch) trips when the system is initially powered on or when the water pump inverter is running. What could be the reason? Water treatment manufacturers also encounter this problem, and the analysis of the reasons is as follows:

Reason 1: Overload

      Overload protection causing tripping is a common reason for tripping. When the current generated by the load exceeds the rated current of the air switch for a long time, the thermal element of the air switch will generate a certain amount of heat, causing the bimetallic strip to bend upwards due to heat, pushing the lever to separate the hook from the latch, disconnecting the main contacts, and thus cutting off the power.

      To solve this fault, let's first look at the current of the water pump inverter while it is running. This can be observed by switching using the shift key. For example, 18.5kW the 8100 running current of the water pump inverter is 37A then using an air switch with a rating of 32A for a long time may cause tripping. At this time, an air switch with a larger rated current can be replaced, such as replacing it with an 40A air switch. The rated current specifications of air switches generally include 5、10、16、20、32、40、50、63A etc.

Reason 2: Short Circuit

      When a short circuit occurs in the circuit, the short-circuit current exceeds the instantaneous tripping setting current value of the air switch (generally 10 times the rated current), the electromagnetic trip unit generates sufficient suction force to attract the armature and impact the lever, causing the hook and latch to separate, thus causing the air switch to trip. After determining that the tripping is not caused by an overload, we can check the circuit for short circuits. Use a multimeter to measure the output end of the air switch to see if there is a short circuit; or use a multimeter to measure the rectifier bridge of the water pump inverter to check if the rectifier bridge is broken down. If the rectifier bridge is broken down, replace the water pump inverter or return the faulty unit to the factory for repair.

Reason 3: Leakage

      If it is neither an overload nor a short circuit, but tripping still occurs, it may be caused by leakage.

      In variable frequency constant pressure water supply systems, many engineers install leakage switches. Because the water pump inverter will have slight leakage during operation. When the leakage current generated by the water pump inverter is greater than the leakage capacity of the leakage switch, the leakage switch will trip. At this time, we can reduce the carrier frequency parameter of the water pump inverter, or replace it with a leakage switch with a larger leakage capacity, or directly replace the leakage switch with an air switch, so that the water treatment equipment can work normally.