Before installation, use a 500V megohmmeter to measure the insulation resistance between the lead wire of the heating rod and the metal shell. The cold-state value is recommended to be no less than 50MΩ. If it is lower than this value, check the end seal or perform drying treatment. The withstand voltage test is conducted at 1500V/50Hz for 1 minute; no breakdown or flashover is considered qualified.
When regulating voltage with the matching control cabinet, the voltage should be gradually increased from the minimum value to the working value, and operation should begin only after the ammeter changes smoothly. The WQJ low-voltage control cabinet must not switch voltage gears under load. The main circuit must be cut off first, and after the indicator light goes out, the gear can be changed to avoid arc damage to the contacts.
When the heating rod is inserted into the center hole of the bolt, the fit clearance should be controlled between 0.2mm and 0.5mm. Too large a clearance affects heat transfer efficiency, while too small a clearance makes disassembly and assembly difficult. When tightening, tighten in diagonal sequence in stages. Refer to the bolt specifications for torque values: approximately 450N·m for M36 and approximately 800N·m for M48, to avoid bending of the rod body caused by one-sided overload.
The DJR-450 type commonly has a power of 1.5kW to 6kW, and the surface load is recommended not to exceed 3.5W/cm². When heating large bolts, the temperature rise rate should be controlled within 5℃/min to prevent local overheating. If used for heating water tanks or oil tanks, the power must be calculated according to the volume and heating requirements to avoid long-term overtemperature operation.
Uninstalled heating rods should be stored in a dry and ventilated place to prevent the insulation layer from becoming damp. Check quarterly whether the terminal blocks are loose or oxidized, and measure changes in insulation resistance. If cracks or deformation are found on the shell, stop using it and replace it.
