Capacitor Color Coding With Examples

Introduction

Capacitor Color Coding With Examples- Similar to resistors, certain marks (bands, dots, or points) are also designed on capacitors employing which its capacitance and other characteristics, e.g., voltage ratings, tolerance, etc., could be distinguished. The method of ascertaining the rating and other characteristics of a capacitor is called color coding. However, the method of color-coding is not so popular nowadays. Now, ratings, general values, capacity, etc. of nearly all types of capacitors are printed on capacitors, even polarity is also indicated in the case of polarized capacitors. Normally, a color-coding system is used on mica and ceramic capacitors. The value of color-coded capacitors is always expressed in pekoe farads.

The value of ceramic disc capacitors having a value less than 1000 pekoe farads, is generally printed above it in figures shape. For example, just 200 is written on a capacitor having a value of 200 pekoe farads. The capacitors, having a value of 1000 pekoe farads or higher, values are written in the form of three digits, e.g., 102 and 105, etc. The method of reading these values is as follows;

102 means 10 x 102 = 1000 pekoe farads

105 means 10 x 105 = 10,00000 pekoe farads = 1 μF

The dots or bands shown in a 5-color coding system, represent a capacitor’s value in the following sequence;  

Color Code for Ceramic Capacitors

Capacitor Color Code

Multiply by 10 for tabular paper capacitors

The first color indicates the first digit of a capacitor’s value, the second color indicates the second figure of a capacitor’s value, whereas the third color indicates the number of zeros (multiplier) used with the first two figures. In other words, the first three colors indicate the capacitance of a capacitor, the fourth color capacitor’s capacity, and 5th color indicates voltage rating. The value of a capacitor can be found by means of the following tables.

Capacitor color coding can easily be understood with the help of the fig. 6.51.

Troubles in Capacitors

Normally two types of defects are found in capacitors, i.e., open and short. In both these conditions, a capacitor becomes useless. Because it cannot store energy when it becomes open or short.

The dielectric resistance of a fine and accurate capacitor tends to be very high. In the situation of paper and ceramic capacitors, the dielectric ranges tend to be from 500 to 1000 megaohm, and in the case of electrolytic capacitors, its value tends to be around 0.5 megaohms. The resistance of a short-circuited capacitor tends to be zero. That’s when a short circuit capacitor is checked with an ohm meter, it denotes continuity. The resistance of a leaky capacitor tends to be slightly less than its normal value.

Checking the Capacitors

An ohm meter is generally used for checking a capacitor. The techniques being utilized for checking capacitors is as follows;

1. Discharge the leads of a capacitor before checking by mutually shorting them.
2. While setting the knob of an ohm meter, it must be ensured that the ohm meter’s voltages do not exceed the working voltages of a capacitor.  
3. Disconnect one side of the capacitor from the circuit, so that every parallel resistance path abolishes. As a result, resistance reading may decline.
4. Keep your fingers away from the conductor, because the resistance value will fall by means of touching human body resistance (50-kilo ohm) in parallel.     
5. Use the highest ohm scale.

The possible defects found in a capacitor can be detected through the following readings of an ohm meter;

1. If the meter’s pointer stops immediately after reaching zero, then the capacitor is short-circuited.
2. If the meter’s pointer moves initially towards the low resistance side (which indicates the capacitor’s charging) and then its value keeps increasing, until it reflects a lower reading as compared to a normal reading, then it is leaky.
3. If the pointer does not move towards the low resistance side of the scale and moves straight towards infinity, or indicates infinity, then the capacitor is open.
4. If a meter’s pointer first moves rapidly towards the low resistance side of the scale (that indicates the capacitor’s charging) and then moves slowly towards infinity, it means that the capacitor is perfect, and its resistance is high. In figure 6.52, a capacitor has been depicted as having been checked by an ohm meter.

Figure 6.52; Checking a capacitor with an ohmmeter; this check shows a good capacitor.

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