China Suppliers Factory for DC Filtering Capacitor for Medium-Frequency Coreless Induction Furnace
DC-link induction heating capacitor for metallurgical manufacture
- Oil-immersed water cooling capacitor and Dry-type metalized film capacitor 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 furnaces employs natural cooling, eliminating the need for water cooling systems. This design saves costs on cooling systems and maintenance. However, the working frequency and over-current capacity cannot be as high as water-cooled type capacitors.
During ironmaking and steelmaking processes using medium-frequency coreless induction melting furnaces, voltage sags and swells will be kept under 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 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, 1000 times during the lifetime) | ||
| Dissipation factor | tgδ≤0.003 f=100Hz | |
| dielectric loss tgδ0≤0.0002 | ||
| Insulation resistance | Built-in 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)
A1: It is primarily 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.
A2: The dry-type capacitor features natural cooling, eliminating the need for cooling water. This design significantly reduces the installation and maintenance costs of a cooling system, although its working frequency and over-current capacity are lower than water-cooled types.
A3: It ensures that the line currents on the supply side are nearly balanced, maintains flicker contribution below standard limits, minimizes reactive power demand, and prevents voltage sag and swell phenomena during operation.
A4: The expected lifespan is 100,000 hours under rated voltage (Un) and at a hot spot temperature of ≤70 °C, as detailed in the expected lifespan chart.
A5: For altitudes exceeding 2000m, the capacitor must be derated. The capacitance and current values should be decreased by 10% for every additional 1000m of altitude.