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1. Maintenance Medium-frequency furnace The machine needs to be shut down for one week or half a month to check its various performance parameters, enabling us to promptly understand the equipment’s condition. Below are the inspection steps that must be performed daily over the course of one week or half a month.

2. To ensure the machine is used more effectively during operation, it must be:

(1) Use a temperature gun to monitor the temperatures of the thyristors, resistor-capacitor protection resistors, and the operating temperature of the voltage-balancing resistors. The temperature-measuring process is divided into three stages: The first measurement, lasting approximately 5–10 minutes, is taken when about one-third of the power is switched on during the operation of the machine’s first batch of molten steel. The second measurement is taken around the time when the furnace is nearly full of molten steel. Finally, the third measurement is conducted at the end of the smelting process—when the current batch reaches full power today. Of course, to promptly detect and address any issues, it is essential to record the readings from these three temperature measurements. (1) Check daily whether the cable screws are loose.

(2) Before starting up each day, you must confirm that the power water pump and the furnace water pump are both turned on, and that the water pressure in the power cabinet is between 1.5 and 1.7 kg, while the water pressure inside the furnace is between 1.5 and 2 kg.

(3) Keep the area around the furnace water cable clean and free of iron filings and metallic objects.

3. Before starting the equipment, the pump must be turned on 10 minutes in advance to check for any leaks. If any leaks are detected, they should be addressed immediately to avoid disrupting production. 4. If the SCR temperature is found to be abnormal, the cause should be promptly investigated—check whether a broken water pipe is causing poor water flow and overheating, or whether there is dirt buildup inside the SCR tube sleeve obstructing the flow.

5. If the temperature of the resistor in the rectifier’s RC protection circuit is noticeably different from that of other resistors, you should immediately check whether the capacitor has opened circuit or the resistor itself is damaged. Generally speaking, this will cause the reactor to exhibit a noticeable buzzing sound and some vibration when it’s first turned on.

6. When performing weekly or biweekly inspections and maintenance, pay attention to:

(1) The inverter’s RC protection for the aforementioned slot shows no voltage drop, thus preventing the short-circuiting of the non-inductive resistor and subsequent burnout of the KK tube. If you notice anything unusual, immediately secure it with a tie.

(2) The equipment’s screws and water clamps must be tightened once a week to prevent damage caused by dropping or loosening.

(3) Check the hydraulic oil level once a week to ensure it’s not low. Generally, the oil level should be maintained at at least 80%.

(4) Pay attention to the local conditions—some manufacturers have lower water quality. Please ensure that the water distributors inside the medium-frequency power supply cabinet are functioning properly and check for any damaged nozzles. If the damage is severe, it’s advisable to replace the entire distributor assembly promptly. After removal, never attempt to weld individual nozzles onto the machine one by one. Doing so could significantly disrupt production schedules and lead to unnecessary time losses. For open-channel systems, it’s generally recommended to replace the water distributors every three months. If the system is fully enclosed, aim to replace them every six months to once a year, depending on the specific circumstances.

7. When cleaning pipe sleeves, it is common practice to circulate a 20% dilute hydrochloric acid solution through the sleeve for 10 to 15 minutes. After regular cleaning, the sleeve must be flushed once with 100% clean water and then dried thoroughly using compressed air before being put back into service, to prevent the hydrochloric acid from corroding the pipe sleeve.

8. Key points for hydraulic maintenance: When using hydraulic oil, pay attention to both the quantity and quality of the oil. Hydraulic oil generally needs to be replaced every six months, and the filter screen should be cleaned once a month. Please note that there are two filters inside the water pressure station—never allow the bottom of the water pressure station to come into contact with water. Be sure to place the filters on the shelves inside the hydraulic station to prevent metal chips from entering and damaging the pump.