Analysis and Treatment Methods of Several Common Faults of Intermediate Frequency Furnace

Analysis and Treatment Methods of Several Common Faults of Intermediate Frequency Furnace

1. After the oven for a period of time, the shutdown is not easy to start

Fault phenomenon: For a new melting furnace or a knotted diathermy furnace, the furnace can be started at the beginning, and the voltage can be increased to a large value, but after a period of time, the furnace can not be restarted after being shut down, and the voltage also rises after getting up. Not high, sometimes it stops vibrating or overcurrent by itself.

Fault analysis and processing: Most of this fault is a problem between the turns of the inductor.

\u003Ci>a．\u003C\/i> \u003Cb>a.\u003C\/b>\u003Ci>对刚打结好的熔炼炉,由于打结料在烘炉时会产生大量的水分,故使感应器匝间聚集了大量的水珠,造成匝间绝缘降低,此时烘炉电压不应很高,待烘干后再提高电压.\u003C\/i> \u003Cb>For the newly knotted smelting furnace, since the knotted material will generate a large amount of moisture during the oven, a large amount of water droplets will accumulate between the turns of the inductor, resulting in the reduction of the insulation between the turns. At this time, the oven voltage should not be very high. high, and then increase the voltage after drying.\u003C\/b>

\u003Ci>b．\u003C\/i> \u003Cb>b.\u003C\/b>\u003Ci>有的感应器线圈没有浸绝缘漆就直接用打结料打结,这种炉子更要注意烘炉时的水分多少.\u003C\/i> \u003Cb>Some inductor coils are directly knotted with knotting materials without being dipped in insulating paint. This kind of furnace should pay more attention to the amount of moisture in the oven.\u003C\/b>

\u003Ci>c．\u003C\/i> \u003Cb>c.\u003C\/b>\u003Ci>有的打结的透热炉在使用一段时间后,打结料会出现微小的缝隙,此时如果感应器绝缘没有处理好,就会有少量的氧化皮进入感应圈的匝间,造成匝间短路,易产生过流现象.感应器线圈用云母带缠绕再浸漆,烘干,后打结\u003C\/i>\u003Cb>After some knotted diathermy furnaces are used for a period of time, there will be tiny gaps in the knotted material. At this time, if the insulation of the inductor is not handled properly, a small amount of oxide skin will enter between the turns of the induction coil, causing the inter-turn Short circuit, easy to produce overcurrent phenomenon. The inductor coil is wound with mica tape, then dipped in paint, dried, and then knotted\u003C\/b>

2, the reactor sound is loud, dull, unstable when boosting, trembling

Fault phenomenon: the equipment can be started, but the voltage rise is not high, the noise of the reactor is particularly loud and dull, the voltage rises very unstable, and there is trembling. There are overcurrent or overvoltage faults from time to time, and sometimes even burn out the inverter tube, but It is good to disconnect the rectifier part of the inverter circuit.

Fault analysis and handling: Most of these faults are faults with the reactor.

\u003Ci>a．\u003C\/i> \u003Cb>a.\u003C\/b>\u003Ci>电抗器的电感量比正常的大,出现磁路饱和,起不到续流滤波作用,也不能隔开交流和直流端的电流,电抗器线圈匝数比正常的多.\u003C\/i> \u003Cb>The inductance of the reactor is larger than normal, the magnetic circuit is saturated, the freewheeling filtering effect cannot be achieved, and the current at the AC and DC terminals cannot be separated, and the number of turns of the reactor coil is more than normal.\u003C\/b>

\u003Ci>b．\u003C\/i> \u003Cb>b.\u003C\/b>\u003Ci>电抗器气隙板比正常的要薄,电感量变大,此时要加厚气隙板.\u003C\/i> \u003Cb>The air gap plate of the reactor is thinner than normal, and the inductance becomes larger. At this time, the air gap plate should be thickened.\u003C\/b>

\u003Ci>c．\u003C\/i> \u003Cb>c.\u003C\/b>\u003Ci>电抗器的线圈匝间有渗水,匝间绝缘降低出现打火放电现象.\u003C\/i> \u003Cb>There is water seepage between the coil turns of the reactor, and the insulation between the turns is reduced, resulting in the phenomenon of spark discharge.\u003C\/b>

3. After the DC voltage rises above 500V, the DC voltage drops instead

Fault phenomenon: start and run normally, when the DC voltage rises above 500V, the DC voltage drops instead, fluctuates, even overcurrent, and sometimes burns and fuses quickly.

Fault analysis and treatment: This is the problem of the rectifier phase-shift circuit:

\u003Ci>a．\u003C\/i> \u003Cb>a.\u003C\/b>\u003Ci>控制板上的零线未接.控制板上的同步信号电路有的需要零线,如果缺少,就会出现移相偏差,导通角超过0 度,出现上述现象.\u003C\/i> \u003Cb>The zero line on the control board is not connected. Some of the synchronization signal circuits on the control board need a zero line, if it is missing, there will be a phase shift deviation, the conduction angle will exceed 0 degrees, and the above phenomenon will occur.\u003C\/b>

\u003Ci>b．\u003C\/i> \u003Cb>b.\u003C\/b>\u003Ci>用户没有将零线接入柜体或零线虚接.\u003C\/i> \u003Cb>The user does not connect the neutral line to the cabinet or the neutral line is connected.\u003C\/b>

\u003Ci>c．\u003C\/i> \u003Cb>c.\u003C\/b>\u003Ci>整流电路的w4电位器(调节150 度)有问题,当调节过量时,导通角超过0 度.有时控制板上前端给定电路有问题时,也会出现导通角超过0 度 .\u003C\/i> \u003Cb>There is a problem with the w4 potentiometer (adjusted to 150 degrees) of the rectifier circuit. When the adjustment is excessive, the conduction angle exceeds 0 degrees. Sometimes when there is a problem with the given circuit at the front end of the control board, the conduction angle will also exceed 0 degrees.\u003C\/b>

4. It is easy to overvoltage when boosting, or overvoltage and overcurrent occur at the same time

Fault phenomenon: It is easy to start, but it is easy to overvoltage when the voltage is raised, and sometimes overvoltage and overcurrent occur at the same time.

The failure analysis and processing are as follows.

\u003Ci>a．\u003C\/i> \u003Cb>a.\u003C\/b>\u003Ci>启动时容易过压,说明逆变引前角过大,造成逆变毛刺电压过高,易使过压保护动作.在扫频电路中,过压后有使逆变桥直通放电功能,此时如果电流也大,则过流保护也会动作.\u003C\/i> \u003Cb>It is easy to overvoltage when starting, which means that the inverter lead angle is too large, which causes the inverter glitch voltage to be too high, which is easy to make the overvoltage protection act. In the frequency sweep circuit, the inverter bridge has a direct discharge function after overvoltage. If the current is too large, the overcurrent protection will also act.\u003C\/b>

\u003Ci>b．\u003C\/i> \u003Cb>b.\u003C\/b>\u003Ci>电源柜体内部的主电路有虚接,绝缘降低,打火现象.\u003C\/i> \u003Cb>The main circuit inside the power cabinet has virtual connection, insulation reduction, and ignition.\u003C\/b>

\u003Ci>c．\u003C\/i> \u003Cb>c.\u003C\/b>\u003Ci>负载线圈或电容器有虚接,绝缘降低,打火现象.\u003C\/i> \u003Cb>The load coil or capacitor has a virtual connection, the insulation is reduced, and the ignition phenomenon occurs.\u003C\/b>

\u003Ci>d．\u003C\/i> \u003Cb>d.\u003C\/b>\u003Ci>逆变晶闸管触发有不可靠因素,连线松动或门极\u003C\/i>\u003Cb>There are unreliable factors in the triggering of the inverter thyristor, the connection is loose or the gate\u003C\/b>

5. What is the reason for the high frequency after the intermediate frequency is started

Fault phenomenon: it can be started, and the frequency is much higher than the original after successful startup, and sometimes it is not easy to start.

Fault analysis and handling: Most of these are load problems.

\u003Ci>a．\u003C\/i> \u003Cb>a.\u003C\/b>\u003Ci>负载线圈匝间有短路现象,可能线间搭接或有导电铁屑,铜丝等.\u003C\/i> \u003Cb>There is a short circuit between the turns of the load coil, and there may be overlap between the wires or conductive iron filings, copper wires, etc.\u003C\/b>

\u003Ci>b．\u003C\/i> \u003Cb>b.\u003C\/b>\u003Ci>负载电容器有柱子开路,或电容连接线有严重打火,造成内部容量发生变化\u003C\/i>\u003Cb>The load capacitor has an open circuit, or the capacitor connection line has serious ignition, causing the internal capacity to change\u003C\/b>

6. What is the reason for burning the intermediate frequency transformer?

Fault phenomenon: The intermediate frequency transformer is burned out, and the starting equipment still burns out the intermediate frequency transformer after the replacement.

Fault analysis and treatment: This kind of fault is common in equipment using boost load, mainly due to the open circuit of the discharge inductance.

In the boost load, the voltages at the two terminals of the series capacitor bank and the parallel capacitor bank cannot be the same. When the two sets of compensation capacitors are discharged, due to the inconsistent terminal voltages, the discharge time is different, and the discharge time with high voltage is slow. , and the charging process begins when the capacitors have not been fully discharged, and DC charges will accumulate on this capacitor bank. These DC charges must be released through the discharge inductance. If the discharge inductance is open, the DC charge accumulated on the capacitor will accumulate It will be released through the intermediate frequency transformer. Because the capacity of the intermediate frequency transformer is small, it cannot withstand such a large current flow, causing the intermediate frequency transformer to burn out.