Equipment electrical maintenance knowledge

2020 new series intermediate frequency furnace installation and commissioning steps

Time: 2019-07-02

1. New series intermediate frequency furnace installation

  (1) No special requirements are required for installation of this unit.

  (2) Only need to be installed in a well ventilated area. For easy maintenance.

  (3) It should maintain a certain distance from neighboring equipment;

  (4) Each device shall be subjected to technical test according to technical conditions before leaving the factory, but there may be vibration during transportation, causing loose wire ends and loose screws, which shall be trimmed and reinforced before debugging;

   (5) Check the installation of inlet and outlet water of each part;

   (6) The capacitor cabinet should be installed close to the induction coil;

   (7) The frequency conversion power supply cabinet and capacitor rack should be installed vertically. It is recommended to use the trench in the lower part of the cabinet to place the cable, busbar and inlet and outlet pipes, and connect the cabinet and the trench to the whole, and the cable for the power cabinet and capacitor rack. Shorten it into one.

   (8) Other final matters shall be in accordance with the electrical installation standards.

2. New series intermediate frequency furnace debugging

Connect the intermediate frequency furnace debugging program, first adjust the control loop, and then adjust the main loop. Before commissioning, use a multimeter to check whether the parts are short-circuited to the ground and whether the thyristor is damaged.

(1) Proofreading phase sequence

The phase sequence of the incoming end is measured by a dual trace oscilloscope, and the difference between each phase sequence is 120 degrees. The three-phase incoming lines of A, B and C should be consistent with the phase sequence required in the cabinet.

(2) Debugging of the control loop

Close the control power supply, but do not press the "Main Circuit Pass" button.

1. PLC machine control program input;

2. Use an oscilloscope to check the correctness of the rectified pulse.

(3) Check the inverter trigger pulse

1. Use an oscilloscope to measure the excitation frequency f and adjust the potentiometer so that the excitation frequency is slightly larger than the natural frequency of the load;

2. Measure the inverter trigger pulse with an oscilloscope, and the diagonal thyristor pulses are in phase, and the adjacent angle pulses are 180 degrees out of each other.

(4) Check the starting circuit

1. Extracting the rectifying phase shifting power amplifier board and the inverter power amplifier board;

2. Connect the oscilloscope probe to both ends of the IF output U and V. After pressing the “main loop” and “power”, the oscillating waveform can be observed to calculate the natural frequency f.

Or: Use a multimeter to measure the voltage of the charging capacitor and quickly discharge it to zero after the “power”.

3. Main circuit debugging

(1). Rectifier main circuit debugging

Disconnect the inverter part, pull out the inverter adjustment control board, and short-circuit the lower end of the reactor.

  Or connect the pig iron resistor, and run the PC program only to the starting current reference, press “Main

  The circuit is combined with the "power" button, the reactor has a sound, and the oscilloscope is used to observe the rectified output.

  The waveform can indicate whether there is a problem with the rectification section.

(2). Commissioning of the inverter circuit

The inverter circuit is reconnected, check whether the load connection is intact, and whether there is a short circuit between the sensors. Adjust all potentiometer parameters first. Press the operation function button. If the startup is successful, each table has a corresponding indication value. The oscilloscope can observe the frequency waveform of the intermediate frequency. If the vibration fails, it indicates that there is a problem in the inverter part, and the fault should be checked before restarting.

    Attachment: If the equipment is overhauled, after replacing the three-phase cable incoming line, please adjust the phase sequence of A, B and C of the three-phase cable before re-use; if the synchronous transformer is damaged, please change the synchronous transformer of the same output voltage amplitude. And use the oscilloscope to check its name end, and the connection is correct before starting the device.

Understand Wikipedia: induction furnace
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