The controller keeps on monitoring the application requirement in a continuous control loop. It then commands the inverter to produce the required voltage and frequency to meet the application requirements. To do this, the controller, comprised of a microprocessor, takes the input signal from the sensor and compares this with a reference signal. It then generates the appropriate control signal for the inverter to vary its output power.

In a typical application, the controller will monitor process parameters such as pressure, flow rate, temperature or liquid level. For example, an oxygen sensor in a boiler provides a signal to adjust the speed of the fan and control the amount of oxygen in the boiler system.

Today’s drives, using microprocessors, semiconductor power switches, and SMDs are now smaller, compact, cheaper, more reliable and efficient. A typical drive will also include a filter to suppress harmonics generated when converting the DC to AC voltage.

We usually expect to find wiring troubles in old homes where the wires are made from out-of-date material that is no longer up to code. But electrical repair needs can crop up in the most modern homes: all it takes is a bit of shoddy installation or damage to a few connections and you can end up with wiring that malfunctions, leading to power loss or—in the worst case scenario—an electrical fire.

Do not attempt any repairs to your wiring yourself unless you are a trained electrician with access to pro-level tools. High-voltage shocks are something to take seriously. Pick up your phone instead and put in a call to your local electrician and arrange for repairs.