Operation Manual

THE INDUCTION HOB
Technical training
- 23 -
CU3-INDUCTION-003UK-10/05
GENERAL
OPERATION
For this purpose, the same components are almost always used: Filtering capacitors, fuse(s), VDRs,
high-inductance choke coils and an indispensable grounding.
• VDR (Voltage Dependent Resistor) begins conducting at 275 or 420 Volts (according to the
model) and eliminate voltage peaks.
• The fuse preventing overcurrents is done so using a restriction on the board pad (Fuse pad).
Actually, there are two series-mounted fuses. Only the IX1 generation is protected by a cartridge
fuse, it is a so-called ‘Very rapid’ fuse.
• Choke coils have a ‘damping’ role that only allows low frequencies. Their action is complemented
by 1µF capacitors.
• The grounding is used to evacuate high-frequency interference ‘residues’.
7.4. - Rectifier
To supply the inducers, it is necessary to apply a high frequency. To change over from 50Hz to 50KHz it is
first necessary to rectify the main voltage through a diode bridge. A filtering capacitor (of 5µF generally) is
associated in order to attenuate the high-frequency signals. As shown by the illustration, the rectifier output
voltage is approximately the main peak voltage (i.e. 310 VDC approx.) when no inducers are supplied. This
voltage drops during the operation.
7.5. - Inverter
The inverter is used to transform a DC signal into an AC signal with
adjustable frequency. The inverter consists of two transistors (whose
technology can vary according to the hob generation), two capacitors
and two recovery diodes (indispensable on any inductive circuit).
Transistors are frequency controlled by a generator. This frequency
varies between 25KHz (for 2800W) and (50KHz for 500W).
The screw attaching the filter has thus an essential role and shall be
imperatively reinstalled after any action