Will the starting current of the electric heating tube be large? If it turns on once every 2-3 seconds and turns off once every 2-3 seconds. The air switch, contactor, and wire will heat up.
The main switch is connected to a 32-flat aluminum wire. This main switch drives a three-phase 4KW motor and three three-phase 4KW heating tubes. Both the heating tube and the motor use 16 flat aluminum wires. The contactor is 30A. The motor does not start frequently, but the heating tube will start frequently, sometimes even turning off for 1 second, then turning on for 2 seconds, turning off for 1 second, and turning on for 2 seconds.
Is it because of such frequent startup that the wires, switches, and contactors heat up? And will the starting current of the stainless steel heating tube be as large as when the motor starts? Is there any way to solve this fever problem? There is a voltage indicator, because there is a transformer next to me, which is connected to three-phase four-wire. The voltage display is about 400V-420V, and the current is maintained at about 8-10A after the motor runs. Is it because the voltage is too high?
PTFE heating tube PTFE heating tube
The chief technical engineer of YIWU JINBAO HEATING PRODUCTS FACTORY summarized the following four points:
(1) Frequent starting will have less impact on the MCB, but may affect the service life of the contactor. Especially the frequent start and stop of high current.
(2) Transition elements, such as copper-aluminum joints, should be used to connect the aluminum wire and the air switch. Otherwise, there will be galvanic corrosion, which will increase the contact resistance and increase the heat generated there, which will burn out the electrical appliances and wires. This kind of failure spreads outward from the point of failure and is not difficult to find.
(3) Electric heating tube, especially refers to resistance wire heating tube that has starting current. As we all know, the cold and hot resistance of a resistance wire are different. Generally, the resistance value of the hot state can be calculated by knowing the power of the tube, and the cold state value can be directly measured. It is recommended to use a high resistance meter. Practice has proved that the cold state value will be less than the hot state value, and the hot wire of some materials will be very different. This produces the so-called starting current. Perhaps the process is short and ignored by everyone. But if the heat preservation starts after reaching the set temperature, the starting current can be ignored.
(4) According to the information you provide, in addition to galvanic corrosion, there is still margin for other parameters. Check whether there are broken strands, joints, or other factors that affect conductivity. In fact, the mechanical strength and aging resistance of aluminum wires are much worse than copper wires.
