RC Element

What is an RC Element?

An RC element is a basic order of electric components in electricity. It contains a resistor and a capacitor and can be complemented with other electric components to get certain functionalities. The name RC component consists of: R for resistor and C for capacitor. The task of the RC element can be potential equalization and limiting electro magnetic inference. A RC element can be used for fail clearance.

An RC component can be used to set up a suppressor circuit. A suppressor circuit protects electric components against voltage peaks which may appear when switching off inductive loads (e.g. relay coil). The suppressor circuit including an RC element is part of the essential protective measures for fail clearance of electric circuits. An RC element fail clearance helps to protect investments in machines and plants and guarantee a fail free process of production.

RC Element Basics

Voltage peaks may be caused by self induction when a coil is switched off. The suppressor of the contactor is used in engine control units since the high inductivity of the contactor may cause high induction voltage during switching off. These can damage electric components. The suppressor circuit of an inductivity can be set up with different components. It can be set up with a diode, a Zener diode, a varistor or simply with a resistor. For the suppressor, an RC element on the contactor is the simplest and most efficient solution.

In magnetic valves, the valve piston is powered by an electro magnet. When switching of the magnetic valves the inductivity of this electro-magnet can create high voltage peaks. Here, a suppressor is equally important. If an RC element before the valve is used as a suppressor, negative effects for neighboring switching element can be avoided.

How does an RC Element work?

Resistors and capacitor are part of the basic elements of electricity. An RC element is set up of these elements. The electric components in the RC element can be set up in multiple combinations as a functional circuit. A passive RC element is not enhanced the signal since there are no enhancing elements in the circuit.

The RC element can be used as a filter. If parts of signals which are over a limit frequency are filtered out it is called low pass. A high pass filters unwanted signal parts under a limit frequency. A low pass equals a parallel circuit of a capacitor on the signal output. A high pass is created by a parallel circuit of a resistor with the output.

The behavior of the RC element can be adjusted by the capacity of the resistor. The higher both values are the time increases in which the capacitor is fully charged. If the input voltage on the RC element is switched off the capacitor starts to discharge. The discharge happens in form of an exponential curve. The curve depends on the time constant which is the product of the values of resistance and capacity.

If an alternating voltage is connected to the input of the RC element, an alternating voltage also has to be connected to the output. It is phase shifted in regards to the input signal. The phase shift on the RC element depends on the frequency of the alternating current.