project name

Series induction furnace

Parallel induction furnace

Power factor

High power factor:. ≥0 95, because the series rectifier intermediate frequency furnace of all SCR are in the fully open state

Low power factor:≤0 .92, because the rectifier and intermediate frequency furnace with all SCR are in a semi-open state (according to the national grid requirements need to add extra compensation)

Output voltage waveform

Rectangular wave

Sine wave

Output current waveform

Sine wave

Rectangular wave

Induction coil fundamental voltage

Q× inverter output voltage

Inverter output voltage

Induction coil fundamental current

Inverter output current

Q× inverter output current

DC filter

Large capacitance

Large reactance

harmonic

Low harmonics, low pollution to the grid

High harmonics, large pollution to the power grid

effectiveness

High efficiency can be 10%-20% higher than parallel power supply

Low efficiency because of low power factor and large harmonic pollution

start up

Startup success rate is 100%

Because the series resonant power supply is frequency modulated, the power is adjusted by adjusting the frequency of the inverter, so the starting rate is high. 
 

Start success rate<100%

It is difficult to start the device under heavy load conditions.

use

Easy to use

Series resonant power supply can realize one-to-one, one-to-two, one-to-three, and other working modes

Inconvenient to use

The parallel resonant power supply can only achieve one-to-one operation mode.

protection

Complete protection

Overcurrent protection, overvoltage protection, phase loss protection, high water temperature protection, low water temperature protection, high water pressure, low water pressure, etc.

Complete protection

Overcurrent protection, overvoltage protection, phase loss protection, high water temperature protection, low water temperature protection, high water pressure, low water pressure, etc.

Reliability

High reliability

Proven reliability exceeds parallel resonant power supply in field use

High reliability

The technology is more mature than the series resonant power supply. 
 

Equipment cost

High equipment cost

Because the tank current passes through the thyristor filter, it uses capacitive filtering.

Low equipment cost

Energy saving

10% to 20% energy saving compared to parallel power supply

Relative series is not energy efficient.