Installation and commissioning technology of new 1 ton parallel melting furnace in 2018

First, reliability

Reliability of 1 ton parallel melting furnace

[1], high reliability. Since the thyristor is a back pressure self-shutdown element, it is not easy to reverse-transform to failure, and the protection action is instantaneous. The service life ofthyristors is semi-permanent under the management of high technology. It can be operated for a long time without failure.

[2], power saving. Since the parallel circuit is used and the reactive current is designed to be small, the power consumption is greatly reduced.

[3] After fully grasping the application technology of thyristor , compared with IGBT , it is easier to realize single-machine large capacity with thyristor , easy to reduce manufacturing cost, and there is no risk of after-sales service.

[4], parallel inverter circuit completed with thyristor , carefully applied high technology, can design extremely simple circuit, easily complete single power supply dual output, realize "one for two", easy for the operator to grasp, easy to maintain .

[5], easy to operate.

[6], no pollution to the power grid, complete set of parallel intermediate frequency electric furnace has high power factor to the power grid, no need to add any compensation measures, the power factor of the integrated electric furnace parallel medium frequency electric furnace to the power grid is maintained at 0.97±2% in the whole process of operation. .

[7], reliable start. The thyristor is a fully controlled device, and its turn-on and turn-off can be achieved by controlling the voltage change of the pole. Therefore, the starting performance is good, regardless of the charge in any state, it is a successful start.

Second, the conditions of use of the surrounding environment

This device is required to be used under the following conditions:

1, The altitude is no more than 1000 meters.

2, The environment is well ventilated, the ambient temperature is not lower than +5 °C, and does not exceed +40 °C.

3, During the deactivation of the unit, the cooling water must be drained and the ambient temperature is not lower than -30 °C.

4, The relative humidity of the weekly network does not exceed 85%.

5, The grid voltage fluctuation is not more than ± 5%.

6, This device is only used in the case of no conductive dust, no flammable or explosive, no corrosive gas and steam.

7, Use indoors without strong vibration and shock.

8, The inlet temperature of the cooling water is +5°C~+35°C, the outlet water temperature should not exceed +40°C, the inlet water pressure should be 0.08~0.1Mpa, the pH value of the cooling water pH is in the range of 6~8.5, and the hardness is not more than 8 degrees. It contains 10 mg of CaO per 1 liter of water per degree. The insoluble matter does not exceed 0.03 mg/l and cannot be used in the case of condensation.

Third, the description of the main technical parameters of the 1 ton parallel melting furnace :

1, The electrical efficiency of the device is not less than 96%

2, 100% rated output, continuous or intermittent operation.

3, Line type: AC (power frequency) DC IF AC (bridge parallel inverter).

Fourth, the basic principle of 1 ton parallel melting furnace circuit

1 ton parallel melting furnace device, the main circuit principle is to input three-phase power frequency AC power from the power grid, through the silicon diode three-phase rectifier bridge, full-wave rectification becomes pulsating DC power, and filtered by C _d , L _d into smooth DC power, send the half-bridge inverter composed of the thyristors from passive to active, a reverse into a desired AC output end of the inverter bridge to the parallel oscillation of the inductor L and the capacitor C consisting of the compensation circuit. The output frequency of the device is controlled by the regulation frequency f _{1 of the} main control circuit , and is also related to the natural oscillation frequency f _{o of the} LC parallel oscillation circuit . When f ₁ =f _o , the required maximum power can be output. When the load parameter changes, the main control circuit automatically controls f ₁ to track the change of f _o to ensure that the maximum power is output at the moment. The power adjustment of the device is realized by adjusting the working state of the inverter bridge through the main circuit, and the adjustment is convenient and flexible. Rectification trigger circuit. The three thyristors in the three-phase half-controlled rectifier bridge are used as electronic fast switches.

During the operation, a pulse of 10 kHz is outputted from the pulse oscillator to open three thyristors, and the rectifier bridge is used for uncontrolled full-wave rectification. When the operation needs to be stopped or protection is required, the rectification pulse is automatically blocked to open the fast switch. Inverter control circuit. With thyristor control, frequency control, power control, IF current limit control, IF voltage limit control, IF overcurrent protection, power frequency overcurrent protection, ground protection, water pressure upper and lower limit protection, grid overvoltage and undervoltage protection, etc. . Various protections are achieved by blocking the rectification pulse and the thyristor gate pulse.

Five, 1 ton parallel melting furnace structure description

1. The device is a cabinet structure.

2. The front right door is the main power switch, the control power switch, the rectifier circuit, and the lower part is the filter reactor.

3. On the front left door, install DC voltage meter, DC current meter, medium frequency current meter, start button, stop button, power adjustment knob, etc.

4. Install the inverter above the front left door and the intermediate frequency capacitor bank below.

5. Install the control system on the front right door.

Sixth, 1 ton parallel melting furnace installation and commissioning

[1], installation

1. When installing, it must be trimmed due to transportation, such as loose wire, loose bolts, solder joints or

The device can be used if it is damaged or not, and if it is treated well.

2, the power cabinet needs to be installed in a well-ventilated, non-water vapor attack, no conductive dust, no oil gas

In the source room, the ambient temperature is +5 ° C ~ +40 ° C, and the distance from the wall should be greater than 1 m.

3. Connect and check the waterway, water quality and water pressure should meet the requirements, and the water pipes should be bent and blocked.

[2], debugging

The 1 ton parallel melting furnace must be commissioned before use. Follow the steps below to check the inverter:

1 power supply for the control part (note: do not connect the large air switch of the main circuit), press the inverter start button (green button) on the cabinet door, adjust the power adjustment knob clockwise to the maximum position, observe with a two-wire oscilloscope Whether the driving signal on the gate of each thyristor module is normal (the square wave with pulse is about 50%, the top of the pulse width is about +15V, the rest part is about -8V. The rising edge and falling edge are within 1μS, the bridge arm is up and down. The dead zones of the two thyristor gate pulses are greater than 2 Μ s), and confirm that the thyristor drive signals of the same bridge arm are in phase (the error of the upper and lower edges cannot exceed 0.5 Μs), and the upper and lower arms can The silicon controlled drive signal must be inverting.

2 check of the rectification pulse. Press the start button, the gates of the three SCRs should have a column of pulses, the amplitude is greater than 1.8V, the pulse width is 50%, and the pulse frequency is about 10kHz.

3 pressure test. Large air switch with main circuit (do not control voltage switch). At this point, the pointer of the DC voltmeter should be raised to 500V or more. Observe whether the parallel melting furnace is normal (no abnormal sound, no odor, no breakdown of each device), keep it for 10 minutes, and the parallel melting furnace is normal. Main power switch. At this time, the DC voltage automatically drops to zero.

4 Start the inverter by following the steps below.

Pass the cooling water and check if the cooling water passages are normal. Turn the power adjustment knob counterclockwise to the minimum position, and then combine the water pump switch, the control power switch, and the main power switch. Note that the DC voltage meter can rise to nearly 500V with the charge. Press the start button and delay 2 seconds to start in the right inverter. The relevant tables should have corresponding instructions. Gradually increase the power adjustment knob clockwise, and the DC current and power meter indications immediately increase and reach the given value. At this point, the parallel melting furnace has entered normal operation. The personnel of the parallel melting furnace production plant will adjust the set values of the protection to the required values (the parallel melting furnace has been basically adjusted before leaving the factory, and can be adjusted as needed at the site).

5 main control board potentiometer description

P ₁ - modulation frequency current waveform hook head, so that nearly sinusoidal, and leaving about ²⁰⁰ angle.

P ₂ - Adjust the mid-frequency current cutoff value.

P ₃ - Adjust the frequency of the current frequency current.

P ₈ - Adjust the value of the intermediate frequency current protection value.

P ₉ ——The size of the current frequency protection value.

P ₁₀ - Frequency meter calibration.

6 Stop as described below.

First turn the power adjustment knob counterclockwise to the minimum position, press the inverter stop button, and the medium frequency sound stops immediately. Turn off the main power switch. At this time, observe that the DC voltmeter drops to zero, and then turn off the control power switch and water pump switch.

7 main control board signal indicator description:

8 external protection board signal indicator description:

9 Warning: After the main power switch is turned on and the inverter is started, it is forbidden to test any part with an oscilloscope or with a meter. Otherwise, the fault will be caused by the access of the parameters outside the test end of the instrument.

Seven, 1 ton parallel melting furnace maintenance and overhaul

1, The parallel melting furnace is inspected once a month to remove dust and dirt from the machine, and check whether the bolts on the thyristor module and the main circuit energizing circuit are loose and damaged. If it is loose, it should be repaired before use. Keep the cabinet clean and bright.

2, If the parallel intermediate frequency electric furnace is not used temporarily, the drying measures should be strengthened, the ventilation should be strengthened to prevent the parallel melting furnace from being damaged by the tide , and the electronic components should be degraded. In winter, the accumulated water in the system should be eliminated to prevent freezing and damage to the pipeline.

3. Since the overload capability of the semiconductor power switching device has been set, overload operation is not allowed.

4. During the working process of the parallel melting furnace , it is not allowed to have any contact line (short circuit) in the output circuit (inductor coil) and the machine, otherwise the parallel melting furnace will be damaged.

5, the machine needs to adjust the parameters in a timely manner, so the user does not need to adjust any electrical equipment during maintenance. If the components are damaged and replaced correctly, they can be put into operation immediately.

6. The user unit should be equipped with special operation and maintenance personnel, and other personnel should not move. In case of human failure or failure expansion.

7, the user unit should be equipped with maintenance instruments, such as multimeter, 20MHz dual trace oscilloscope.

8. The fault of the parallel melting furnace is easy to judge, and the thyristor module is not easily damaged. The CE two-pole resistance value of the thyristor module can be measured by a multimeter . Generally, the thyristor module is considered normal as long as the two poles of the CE are not short-circuited . If the thyristor module CE is short-circuited, the information about the indicator light and the output signal of each control board can be checked to find out which board the fault is on, replace the new board, and repeat the operation of the “debug” part. can.

9. In summer, because the inlet water temperature is too low (compared with room temperature), condensation is likely to occur in the power cabinet. At this time, it is necessary to stop immediately, and try to increase the inlet water temperature until the condensation is removed.

10. Keep the ventilation inside the machine so that the components on each control board dissipate well.

11. In the power cabinet, if the surface of the circuit is covered with conductive dust, the oil should be cleaned with acetone or alcohol in time to ensure trouble-free operation of the parallel melting furnace .