Induction Furnace Upgrades

Induction furnace upgrades can solve many existing problems in induction furnace plants. In order to provide users with the highest safety, energy-saving, and easy-to-operate induction furnaces in the industry, our company also provides induction furnace upgrades services.

1. The Common Faults of the Induction Furnace during Operation.

(1) No response from the system during the startup

① Rectifier board failure;

② Overcurrent and overvoltage protection actions;

③ The main switch is not properly closed;

④ The control power regulating potentiometer is damaged or disconnected;

⑤ The rectifier control power supply is faulty.

(2)Only DC voltmeter has an indication, others have no response

① Inverter board and inverter circuit failure;

② Inverter power failure. There is no 22V power supply for the inverter pulse.

Attention: When the phase voltage of the power supply is higher than 240V, it is easy to damage the control power transformer.

(3) Unable to start successfully during startup, with high DC current and low DC voltage (tens of volts)

① There is a direct short circuit phenomenon in the inverter section (such as short circuit between copper bars, breakdown of electric heating capacitors, etc.)

② There is a problem with the inverter control circuit and signal acquisition part (open circuit or short circuit)

③ Multiple identical damage phenomena exist in the inverter thyristor (a multimeter R can be used × 1st gear measurement).

(4) During startup, there may be occasional frequency sounds, but all instruments oscillate, or after startup, each instrument oscillates. After the power is increased, there may be overcurrent or overvoltage.

① The inverter control board is defective.

② Improper adjustment of the minimum tf working angle.

③ Broken water and electricity cables or loose cable screws.

④ The furnace is short-circuited or grounded, and the voltage circuit may be short-circuited on the output side.

⑤ The thyristor is defective.

(5) When the main circuit is closed, the air will trip at the beginning, or overcurrent protection will be provided. Even if it is normal occasionally, there will be abnormal sounds. One liter of power will cause overcurrent.

① Generally, it is a breakdown of a rectifier thyristor.

② The performance of thyristors decreases, or they lose their ability to block in a certain direction and become diodes.

③ There is a short circuit in the rectifier circuit.

(6) It can be started, but the sound of the reactor is dull. The meter occasionally oscillates, and the DC voltage rises to 500V.

① The main circuit is out of phase (generally, there will be no DC voltage output when the constant power board is out of phase);

② Lack of pulse in the control circuit;

③ One of the rectifier thyristors cannot be connected or maintained, and the gate is open or short-circuited.

(7) Capable of starting, but with a high ratio of intermediate frequency voltage to DC voltage, low voltage, and high DC current.

① A certain bridge wall of the inverter thyristor is broken down;

② A certain thyristor does not work When judging, the voltage drop of the transistor can be directly measured using the AC range of a multimeter when working at low voltage. If there is no voltage, it may break down, but attention should also be paid to whether adjacent bridge walls are not working. For a single tube bridge wall, if the positive and negative phase voltages are the same, it does not work. Relevant circuits can be checked.

For a double thyristor series circuit, there are two situations. For the same single tube circuit, generally, if both transistors have no pulses, and the voltage is one positive and one negative, it indicates that the thyristor bearing the forward voltage The tube is not working, check if there is a control pulse, if the polarity is normal, and if the gate is open circuit.

③ The inverter control circuit is abnormal.

④ Load mismatch or improper setting of minimum TF angle.

Note: When the KK thyristor breaks down, it will cause the secondary parallel diode of the inverter pulse transformer to also break down, causing the inverter pulse to have no output. When replacing with a new thyristor, attention should be paid to checking, as this can also cause the three walls of the inverter bridge to work.

(8)The DC voltage is unstable, or a certain range is unstable, the meter swings, and there is a sound of wire breakage in the reactor.

① The triggering pulse is unstable;

② Poor characteristics of rectifier thyristor;

③ There is poor contact in the main circuit;

④ The PI modulator oscillates due to issues;

⑤ Control circuit guidance interference.

(9) If the intermediate frequency voltage is unstable, eliminate the possibility of unstable DC voltage.

① Poor inverter thyristor;

② Unstable inverter pulse;

③ Improper setting of minimum TF angle;

④ Poor contact or sparking of the corner load circuit;

⑤ There is a problem with the PI regulator and there is oscillation;

(10) Unable to adjust the power (excluding rectifier and inverter faults).

① Load mismatch, too light or too heavy (adjustable load circuit);

② For circuit users who use the crimped connection method, they did not use the crimped connection method to connect;

③ Output wire loss is too large

(11) Normal start, the voltage rises to a certain level, and suddenly there is a lifting phenomenon.

① The minimum angle adjustment is too small;

② Improper frequency adjustment of the circuit board.

(12) A new or cold furnace is easy to start and can work normally, but when the furnace is hot or full of molten steel, there is a shutdown and it is difficult to start.

The main issue is that the frequency adjustment of the circuit board is not suitable, and the angle involved is too small.

(13) If the intermediate frequency device can be started, overcurrent occurs when the power increases. Common reasons:

① If the intermediate frequency transformer is damaged or defective,

② Damaged or defective inverter pulse transformer,

③ Inverter thyristor soft breakdown or intermittent,

④ Leakage of the primary series capacitor of the intermediate frequency transformer,

⑤ Soft breakdown of electric capacitors, poor insulation of furnace coils or copper bars, or slight short circuit.

2. Advantages of Induction Furnaces Upgrads

(1) Safe, sturdy, and efficient furnace structure

The furnace body adopts a seismic resistant (Richter scale 7 standard) structural design, equipped with special structural magnetic yokes and shaped coil conductors to achieve safe and efficient operation of the furnace body.

(2) Built-in fault detection monitor

Multiple sensors constantly collect equipment operation data, and in case of abnormal situations, timely alarm and cut off the power supply for operation. The human-machine interface automatically pops up fault information and guides maintenance personnel in troubleshooting and repair.

(3) Compact and efficient inverter power supply

Compared with thyristor power supply, it saves 2-3% of energy consumption.

Regardless of the output power, it can achieve high efficiency (above 0.98).

Multi-pulse rectification can significantly reduce the occurrence of high-order harmonics, eliminating the need for high-order harmonic processing devices.

Starting from the early stage of cold rolling, the rated power can be put into operation, reducing the melting time by about 6%.

The compact power cabinet design saves land resources and reduces customer initial investment costs.

(4) Easy to operate

Only the “start” and “stop” switches and power adjustment knobs are needed to complete the operation. Supported by a large screen humanized human-machine interface, automatic sintering, automatic preheating, fault management analysis, data export and other functions, it provides support for factory automation production.

(5) High reliability of electronic components

The inverter electronic components use IGBT modules produced by Fuji Electric, and each module undergoes strict temperature changes and vibration tests before leaving the factory. The inverter is composed of several unit groups, which can achieve selective partial shutdown operation and reduce downtime during faults.

If you want an induction furnace upgrades, you may contact us for details.