How to design the power cord of the air conditioner

When selecting the power cord, the power consumption of the equipment must be known, that is, the power consumption (electric power) of the air conditioning unit. With this known condition, use the formula of three-phase alternating current power to find the current, the formula: P (electric power) = √3×380 (three-phase voltage) × I (current) × cosφ, where cosφ is the inductive load The reactive power loss of, you can take a conservative value of 0.85: √3=1.732 This is the basic mathematical common sense, and the current (I) is derived: I=P (power)/√3×380×0.85 (cosφ), there is After calculating the current, find the diameter of the power cord (note that this is the diameter of the wire, not the cross-sectional area. The specifications of the power cord are all expressed by the cross-sectional area).

Wire diameter formula: d=0.8×√I, and then use the wire diameter to find the cross-sectional area of the wire. This is the mathematical formula: radius×radius×3.14; OK, now the calculation is over, the specification of the power cord used Out. Simple, you need to remember two formulas, one: P (electric power) = √3 × 380 (three-phase voltage) × I (current) × cosφ and the other formula: d = 0.8 × √I. The formula is also applicable to the 220V power supply. When solving the current, the power supply voltage in the formula can be changed.

Air conditioner compressor motor failure

Early failures have not been cleaned up: For systems that have had compressor burn-out failures, we must thoroughly clean the system, because the motor will have a strong acid when the motor is burned out and stay in the system. If it is not cleaned, when the new motor is running At this time, RESI diacid will corrode the insulation layer of the motor, causing the new motor to burn out again. barrier. Unstable: The power supply voltage is too low or too low, which will have an adverse effect on the motor, especially if the rated voltage range exceeds the compressor improper use. Long-term operation makes the motor in an inefficient overheating state, resulting in poor insulation and burnout of the motor. In addition, the unbalance of the three-phase voltage or current will also lead to an increase in motor losses and an increase in the temperature of the motor coil. If the protection is improper, damage to the motor insulation will have undesirable consequences.

Compressor rotating parts are stuck: When this happens, if the motor protection fails, the motor may be overloaded and burned out. The compressor is stuck due to foreign matter entering the compressor, there is no oil for lubrication and operation, loose parts, excessive sintered bodies and bearing wear. The compressor starts frequently. Although the motor starts during the starting process, the starting current is still several times the rated current, so the temperature rises very fast during the starting process of the motor. If the cooling range of the refrigeration unit is inappropriately selected, the control exceeds the frequency range of compressor start and stop, so that the compressor frequently shuts down the machine, thereby shortening the service life of the compressor motor.

Poor cooling: The system is too poor to control the return air and overheating, the return air temperature is too high or the return air volume is too low, so that the motor cannot be fully cooled. Starting contactor failure: The contactor is prone to failure or poor quality, resulting in excessive contact resistance or sintering, leading to short-circuit sintering. The production process of the motor is not good: If the compressor motor itself is manufactured defective, the motor is generally burned out in a short time, which may be a problem of the manufacturing itself.