Electrolytic Capacitor – Properties, Uses, Capacitance Value and Polarity

In the previous post, we discussed about Ceramic capacitors. This post will discuss about the Electrolytic Capacitor, its various properties, uses and how to find Capacitance Value and polarity of the terminals.

Introduction to Electrolytic Capacitor

Electrolytic capacitor is named so because the dielectric which is used in it is an electro chemically treated oxide form. Electrolytic capacitor comes under the category of polarized capacitors.

As discussed in earlier post, the term ‘polarized’ means that these capacitors have a positive and negative end, and they should be connected that way only. A wrong connection may lead to abnormality / malfunction / defect in Electrolytic Capacitors due to the breakage of the very thin dielectric layer.

Properties of Electrolytic Capacitor

The various properties of Electrolytic Capacitor are as follows:

Dielectric Constant (K) of Electrolytic Capacitor

Like wise to the case of Ceramic capacitor, The Electrolytic capacitor also has high dielectric constant (K). Due to this, it offers high capacitance values still in reduced sizes.

Temperature Limitation of Electrolytic Capacitor

As this type of capacitor contains an electrolyte jelly in it, it cannot be used below  -40ºC (as the low temperature may lead to the freezing of this jelly) and above +105ºC (as the high temperature may lead to the evaporation of this jelly).

Note: Earlier, I had mentioned -10ºC to +85ºC temperature range. However, I have changed it when my friend Harry (An Electronics Engineer with 10+ years of ongoing experience) updated me about the current development in temperature rating of these capacitors.

Polarization of Electrolytic Capacitor

These Capacitors are polarized. They should be connected such that the electrolyte must always be the negative electrode. With such connection, a small current will flow through the capacitor.

However, if the they are connected vice versa, then it will lead to a flow of large current, which in turn may damage the capacitor permanently.

Cost of Electrolytic Capacitor

They have a very low manufacturing cost.

Size Availability

They are available in various sizes, from a huge one to a smaller one according to the requirement. It is why, like ceramic capacitors, the installation space is not an issue.

Reliability

They are quite reliable and one of the most used capacitors in the capacitor family. They also possess high tolerance value.

Capacitance Range of Electrolytic Capacitor

They are normally available in large capacitance values ranging normally from 01 µF to few farads.

Voltage Rating of Electrolytic Capacitor

They have a very low voltage rating. This is in fact one of the drawback of Electrolytic capacitors.

Uses of Electrolytic Capacitors

They are often used for circuits involving small frequencies. They can be used for: –

• Reducing voltage fluctuations in filtering devices.
• Smoothing the input and output to a filter.
• Noise filtering or decoupling in power supplies.
• Coupling signals between amplifier stages.
• Storing energy in low power applications.
• To provide time delays between two functions in a circuit.

How to Find Capacitance Value and Polarity of Electrolytic Capacitors

The capacitance value and polarity of an Electrolytic Capacitor can be determined as follows: –

Capacitance Value

The capacitance value (as well as working voltage) is clearly written on these capacitors. There is no decoding involved in this.

Polarity

The negative end is indicated with a minus (-) symbol. The other end which is unmarked will be Positive end.

In case, the negative end is not marked with a minus (-) symbol, then you can also identify it by a thin odd color band above it.

In case if both is not available, then you can still identify it by seeing length of both the leads of these capacitors. The length of negative lead is always kept smaller than the positive end at the time of manufacture for its identification.

Also read: -
Types of Capacitors
How to Read Capacitor Color Marking Values - Calculation and Identification Codes