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DC Filtering Capacitor for Medium-Frequency Coreless Induction Furnace - China Suppliers and Factory Solutions
DC-link induction heating capacitor for metallurgical manufacture
- Oil-immersed water cooling capacitor and Dry-type metalized film capacitor and for options.
- Max rated voltage: 3500VDC
- Max capacitance: 10000uf
- Mainly applied for AC current 3-phase 380VAC, 575VAC, 660VAC（internal series power supply），Series resonant induction heating system which frequency lower than 10Khz
Function of DC power induction heating capacitor
- DC-link support;
- Filtering low and high frequency ripple wave;
- Bypass series resonance current;
Feature of dry-type film capacitor for mid-frequency furnace
The dc filtering film capacitor developed for mid-frequency furnace, which employed natural cooling, no need cooling water placed in. The design will save cost on cooling system and maintenance. But the working frequency and over-current can’t be as high as water cooled type capacitor.
While ironmaking and steel making process by medium-frequency coreless induction melting furnace, voltage sags and swells will be in good control.
What is good to use a coreless induction melting furnace?
- Line currents on the supply side are nearly balanced.
- Flicker contribution is below the limits specified in the standards.
- Reactive power demand is relatively low and the variations in the magnitude and rate of change of active power are not drastic.
- No voltage sag and swell phenomena arising from furnace operation.
Power circuit diagram of a typical medium-frequency coreless induction melting furnace
The below picture is dry type capacitor designed for coreless mid-frequency induction melting furnace
General introduction
- Metal shell encapsulation, dry epoxy resin potting;
- Pure copper electrodes, vertical/horizontal installation;
- Compacted design;
- Self-healing metalized dielectric;
- High voltage, High ripple current, high dv/dt withstand capability.
General spec
| Capacitance range |
100μF～20000μF |
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| Rated voltage Un |
600VDC～8000VDC |
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| Capacitance.tolerance |
±5%(J) ;±10%(K) |
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| Withstand voltage |
Vt-t |
1.5Un DC/60S |
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Vt-c |
1000+2×Un/√2 （V.AC） 60S(min 3000 V.AC) |
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| Over-Voltage |
1.1Un(30% of on-load-durability.) |
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1.15Un(30min/day) |
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1.2Un(5min/day) |
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1.3Un(1min/day) |
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1.5Un(100ms every time,1000times during the lifetime) |
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| Dissipation factor |
tgδ≤0.003 f=100Hz |
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dielectric loss tgδ0≤0.0002 |
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| Insulation resistance |
Builtin-discharge resistor |
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| Withstand pulse current |
contact for details |
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| Effective current/Irms |
contact for details |
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| Stray induction/ ESL |
＜150 nH |
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| Flame retardation |
UL94V-0 |
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| Maximum altitude |
2000m |
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The altitude reach above 2000m, the capacitor must be used at derated capacitance and current value, 10% decreased at every increased 1000m |
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| Life expectancy |
100000h(Un; Θhot spot ≤70 °C ) |
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| Reference standard |
IEC 61071 ;IEC 61881; |
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| Operating temperature |
-40℃~+ 70℃ |
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Expected lifespan chart
Frequently Asked Questions (FAQ)
Q1: What types of DC-link induction heating capacitors are available for selection?
A1: Both oil-immersed water cooling capacitors and dry-type metalized film capacitors are available as options.
Q2: What is the maximum rated voltage and capacitance of these capacitors?
A2: The maximum rated voltage reaches up to 3500VDC, and the maximum capacitance is 10000μF.
Q3: What are the main functions of the DC power induction heating capacitor?
A3: Its primary functions include DC-link support, filtering low and high-frequency ripple waves, and bypassing series resonance current.
Q4: What are the advantages of dry-type film capacitors in mid-frequency furnaces?
A4: They utilize natural cooling, which eliminates the need for cooling water. This design saves costs on both the cooling system and its maintenance.
Q5: What are the benefits of using a coreless induction melting furnace?
A5: It ensures balanced line currents on the supply side, keeps flicker contribution below standard limits, maintains relatively low reactive power demand, and prevents voltage sag and swell phenomena.
Q6: What standards do these capacitors comply with and what is their expected lifespan?
A6: They comply with IEC 61071 and IEC 61881 standards, offering an expected lifespan of 100,000 hours under rated voltage (Un) and a hot spot temperature of ≤70 °C.