Introduction:
Capacitors are used in electronic devices such as computer circuit boards, televisions, and radios, but on this page, we apply the concept of ‘capacitor’ to automotive technology. In automotive technology, capacitors can be found in, for example, electronic filters, control devices, level meters, ignition coils, and relays.
A capacitor stores energy. This energy can serve as interference suppression in a radio filter (the capacitor filters certain frequencies, such as dynamo noise), or as a turn-off delay in the interior lighting. When the door is closed, the interior lighting fades out slowly. Voltage fluctuations from rectifiers (diodes) are also smoothed out by capacitors. The capacitor can charge and discharge in a short time.
How the Capacitor Works:
A capacitor consists of 2 (usually metal) conductors separated by the dielectric. This is a non-conductive material such as plastic, or otherwise by a vacuum.
When an electronic voltage source is applied to the plates, both plates will be charged. The left plate (with the -) will be charged negatively, and the right plate (with the +) positively.
The charging current stops as soon as the voltage difference between the plates is equal to the voltage difference of the power source. This charging takes time. This time can be calculated. This will be addressed later on the page.
The charging current stops as soon as the voltage difference between the plates is equal to the voltage difference of the power source. This charging takes time. This time can be calculated. This will be addressed later on the page.
Series Configuration with Capacitors:
In capacitors connected in series, the charge on all capacitors is equal.
Parallel Configuration with Capacitors:
In parallel-connected capacitors, the voltage across all capacitors is equal.
Capacitive Level Sensor:
This example concerns the level sensor in a car’s fuel tank. There is a shared dielectric.
The principle of capacitive level measurement is based on the change in capacitance of the capacitor, which depends on the change in level (in this case, the fuel quantity).
Gasoline is not a conductive substance, so no short circuit can occur between the plates of the capacitor due to conduction, as would be the case with, for example, water.
The capacitance of the capacitor can be determined with a formula. The meanings of the symbols are as follows:
- C = capacitance
- A = plate area
- d = distance between the plates