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DC Filtering Capacitor for Medium-Frequency Coreless Induction Furnace - China Suppliers & Factory Quality 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 | |
| Rated voltage Un | 600VDC～8000VDC | |
| Capacitance.tolerance | ±5%(J) ;±10%(K) | |
| Withstand voltage | Vt-t | 1.5Un DC/60S |
| Vt-c | 1000+2×Un/√2 （V.AC） 60S(min 3000 V.AC) | |
| Over-Voltage | 1.1Un(30% of on-load-durability.) | |
| 1.15Un(30min/day) | ||
| 1.2Un(5min/day) | ||
| 1.3Un(1min/day) | ||
| 1.5Un(100ms every time,1000times during the lifetime) | ||
| Dissipation factor | tgδ≤0.003 f=100Hz | |
| dielectric loss tgδ0≤0.0002 | ||
| Insulation resistance | Builtin-discharge resistor | |
| Withstand pulse current | contact for details | |
| Effective current/Irms | contact for details | |
| Stray induction/ ESL | ＜150 nH | |
| Flame retardation | UL94V-0 | |
| Maximum altitude | 2000m | |
| The altitude reach above 2000m, the capacitor must be used at derated capacitance and current value, 10% decreased at every increased 1000m | ||
| Life expectancy | 100000h(Un; Θhot spot ≤70 °C ) | |
| Reference standard | IEC 61071 ;IEC 61881; | |
| Operating temperature | -40℃~+ 70℃ | |
Expected lifespan chart
Frequently Asked Questions (FAQ)
Q1: What are the primary applications of DC-link induction heating capacitors?
They are mainly applied in AC current 3-phase systems (380VAC, 575VAC, 660VAC) with internal series power supplies, and series resonant induction heating systems operating at frequencies lower than 10Khz.
Q2: What is the main benefit of using a dry-type capacitor over a water-cooled type?
Dry-type capacitors utilize natural cooling instead of cooling water. This design eliminates the need for water cooling systems, significantly saving on maintenance and installation costs, though they operate at lower frequency and over-current limits.
Q3: How do DC power induction heating capacitors function in the circuit?
They function as DC-link supports, filter out low and high-frequency ripple waves, and bypass the series resonance current to stabilize the power system.
Q4: Why is a coreless induction melting furnace preferred in metal processing?
A coreless induction furnace 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.
Q5: What is the expected lifespan of these capacitors under normal conditions?
The expected lifespan is 100,000 hours, provided the capacitor operates under the rated voltage (Un) and the hot spot temperature remains at or below 70°C.
Q6: Are there any special requirements for using these capacitors at high altitudes?
Yes. When used at altitudes above 2000m, the capacitor must be derated. The capacitance and current values should be decreased by 10% for every additional 1000m of altitude.