1. Not grounded
The protection and grounding of small submersible electric pumps are mandatory national standards. Only protective grounding can ensure personal safety during use. If there is no protective grounding, once the shell leaks electricity, the water at the outlet of the small submersible pump and the water surface pumped out will be charged, endangering human and animal safety and wasting a lot of electrical energy.
If the metal casing of a small submersible pump is connected to a grounding body that meets national standards (grounding resistance not greater than 4), when the casing of the small submersible pump leaks electricity, the current will form a closed circuit through the metal casing, protective grounding wire, grounding body, earth, working grounding wire of the transformer, and power supply of the small submersible pump. When the leakage current is too large, especially when the live wire contacts the casing, the protective device of the small submersible pump will be activated (fuse or air switch will trip), and the leakage of the small submersible pump will be cut off.
2. Do not install a leakage protector
Small submersible electric pumps working in water are prone to energy loss and even electric shock due to leakage. If a leakage protector is installed, as long as the leakage value of the small submersible pump exceeds the operating current value of the leakage protector (generally not exceeding 30mA), the leakage protector will cut off the power supply of the small submersible pump.
3. Motor rotates in the opposite direction
At present, there are many types of small submersible electric pumps that can produce water in both forward and reverse directions. However, the reverse direction has a small water volume and high current, and the motor winding will be damaged if the reverse time is long.
Therefore, before entering the water, the submersible pump should be powered on and the rotation direction should be checked for correctness. If the impeller of the three-phase small submersible electric pump reverses, it should be stopped immediately and the connection between any two phases of the three-phase core wire in the cable can be changed.
How to control the noise of small submersible electric pumps?
1. Control from the perspective of pump design
In order to reduce noise, the number of impeller blades and guide vanes should be matched with each other in the design to avoid resonance, and the reasonable radial clearance between the impeller, guide vanes, and volute should be controlled. If these factors are not handled properly, noise will be generated. To reduce noise sources from the perspective of structure and hydraulic design, this ensures the superiority of innate control of sound sources.
2. The installation operation should be reasonable
During installation, strictly follow the installation procedure to prevent sound sources, pay attention to venting, ensure allowable suction or necessary cavitation allowance, control the minimum flow rate of the pump, and avoid overcurrent operation.
3. Increase protective measures
Place shock-absorbing gaskets at the support of the pipe rack, and install soundproof covers around the pump and motor. The soundproof covers are made of soundproof materials, which is relatively simple and fast.
4. Non pulsating muffler
There are two types of double-layer cylindrical non pulsating mufflers: expansion type and phase interference type. They are the appearance of this non pulsating muffler. After installing the non pulsating muffler, the effect is obvious. Due to the installation of the non pulsating muffler, the frequency noise generated by pump pulse robbery is almost completely attenuated.
