- Induction: how does it work?
- Induction hobs: which criteria of choice?
- High power, fine adjustments
- Fans under the inductors
- Installation principle of a cooking plate
- Easy maintenance
- The good use of functions
- Comparative table of eight induction hobs
Fast heating, flexible adjustment, ease of maintenance... induction hobs combine the advantages. Depending on cooking habits, it is possible to opt for two, three or four fireplaces, easy to fit into most worktops.
Launched in the early 1990s, the induction hob is now established in the kitchen. With some 600,000 pieces sold in 2013 *, it takes the first place on the market, ahead of enamel gas, electric or mixed (350,000 to 400,000 units) and the ceramic hob with radiant or halogen fires (about 200,000 rooms).
Even less expensive competitors... This success is due to the indisputable advantages of induction cooking. It provides a faster ramp-up than gas, and temperatures can be adjusted instantly with incomparable accuracy compared to ceramic hobs. In addition, only the cooking zone is heated (see box opposite), which eliminates any risk of burns. Finally, the fireplace will turn off automatically as soon as the container is removed.
Induction: how does it work?
The operating principle of an induction hob is simple. A coil called inductor, consisting of windings (turns) of copper, is placed under each zone (or focus) of the plate. When switched on, the inductor is traversed by a high frequency alternating electric current (20 to 50 kHz) and generates a variable magnetic field.
This reveals electric currents called induced (these are eddy currents) in the ferrous metal bottom of the container, placed on the glass plate. The electrons of the metal move and generate, by "Joule effect", an important release of heat, which is then transmitted to the contents of the pan. In the absence of a container, no heat is produced: even if the induction hob is on, the hob remains cold. Caution, the instructions recommend to people wearing a pacemaker not to approach a working induction table.
GOOD TO KNOW
To bring to the boil two liters of water from 15° to 90° C, it is necessary to count:
• 4 min on an induction hob with a 3.3 kW fireplace, for a consumption of 225 W
• 9 min on a ceramic hob with a 2.2 kW fireplace, for a consumption of 314 W.
Induction hobs: which criteria of choice?
To choose an induction hob, the first criterion to take into account is the size of the hearths.
There are three types of diameter (small, medium and large) generally ranging from 14.5 to 28 cm. Inductor heating only under the pan, we can use a small container on a large fireplace. But not the other way around. Hence the interest of having a large cooking zone, or more interesting (but often more expensive) a flexible zone, which detects the size of the container automatically.
Some high-end models have a single large and rectangular free area: the pan can be positioned anywhere. A concept that, according to professionals, should develop in the future.
If the diameter of the hearths is important, their number is just as determining : a table with three areas (the most sold) is perfect for everyday use. But it can be insufficient if you cook intensively. Better then opt for a model with four homes running simultaneously.
High power, fine adjustments
Another criterion of choice, the total power. Professionals recommend between 6 and 7 kW for optimum efficiency on all heating zones. But some models of lower power (4.6 kW for example) still show good performance, as shown by the results of the tests carried out by the magazine "Que Choisir" *, which tested 113 models.
In any case, the higher the power levels, the finer the setting. This allows to succeed the most delicate cooking. Note that the sensitive electronic controls allow, with a simple touch of the finger, to select the focus and functions of the plate. Their ergonomics determines the comfort of use.
* Comparative published in January 2014 (quechoisir.org).
Fans under the inductors
Induction tables are equipped with one to six fans according to their dimensions (two on average), placed under the inductors. Their installation is within the reach of all. Although cooks recommend the addition of a drawer on the underside, we can now set up without problem above a dishwasher. On the price side, they have become more accessible. Count from 200 € to more than 1,500 €, with an average around 450 €. According to "Que Choisir", "the difference in price is not really justified by the performances displayed by the tables. All induction tables now offer satisfactory performance. "
Installation principle of a cooking plate
The installation dimensions are usually 560 x 490 mm.
The worktop is cut according to the manufacturer's instructions, respecting the safety distances.
With an average of two fans on the underside, induction hobs can now be installed above a dishwasher without the risk of a short circuit.
After each use, clean your table with a damp sponge (wipe to avoid tartar). Avoid aggressive detergents, scouring sponges and metal straw pads. Dried residues are removed with a squeegee or scraper for ceramic hobs (DIY superstores). Then apply a specific cleaning agent for this type of surface (also in GSB). It can be replaced with a mixture of dishwashing liquid and white vinegar, rinsed with hot water and wiped with a soft cloth.
The good use of functions
In addition to the functions dedicated to each home (booster and timer), the plates have seven to ten security options depending on the model. When buying, several functions can make the difference:
• "Bad connection" detection: prevents damage to the device in case of improper installation.
• Anti-overheating: lowers the power and temperature in case of overheating of the fireplace.
• Automatic shut-off: cuts the power supply of the plate in case of abnormally prolonged cooking.
• Residual heat indicator: Lights up as long as the fireplace remains warm.
• Anti-overflow protection: the plate goes out as soon as a liquid overflows and reaches the control panel.
• Container detection: start-up works only if a saucepan is present on the firebox.
• Detection of small utensils: Induction only works in the presence of upper metal surfaces generally at Ø 10 cm.
• Control Lockout: prevents children from changing cooking settings.
Metal utensils are conductive: they must not be placed on an induction cooker. Some models have a very convenient detection function.
The latest generation of "smart" tables offers a large, free and adjustable cooking space, which detects the container and defers the settings in case of movement.
Comparative table of eight induction hobs
Comparison of eight induction hobs