What is a capacitor, and what does it do?

What is a capacitor?

In broad terms, a capacitor is a device that stores electrical energy. They have many practical uses in electronics, such signal processing, circuit decoupling for electrical protection and assistance in the startup of electric motors amongst countless others. They are present in a broad range of electronic devices, and come in a massive variety of shapes, sizes and types.

What is the capacitor in a pressure washer for?

The capacitor is used as a form of starting aid on 1-phase motors. This is a standardized component that is fairly similar on all electric motors, and is present on a range of tools including lawnmowers, chainsaws, high-pressure washers and the like. The differences you will see between motors is the size of the capacitor, which must be adapted to the size of the electric motor.

If a capacitor is damaged, you will experience problems with motor startup, however we very rarely see a broken or faulty capacitor as they are a comparably simple and reliable componant.

Why might my capacitor have broken?:

As a rule, the reason for the capacitor has become damaged is that the voltage supply to the motor is too low. 

Please note that in some garages, sheds and the like there may be thin cables/poor power supply which can cause voltage drops and a large load on the capacitor.

How do you know that a capacitor is broken:

If the capacitor does not work, the machine will make a buzzing sound when you try to start the washer. It will then not be possible to get the engine started and the buzzing sound is reasonably stable every time you try to start. If the buzzing occurs intermittently when the machine is in standby but still starts fine, it is probably not the capacitor that is the problem. In that case, the problem may lie in the pump head.

Please be aware that a buzzing or humming from the machine is a common symptom of many potential issues with a pressure washer, and the capacitor is very often not the cause of the motor failing to start up properly.