 # How to find short circuit currents

Short circuit – the dangerous phenomenon arising at decrease in resistance of a chain to very small size. To find and exclude a possibility of short circuit – an important task.

## It is required to you

• - resistor;
• - tester;
• - current source;
• - consumer of current.

## Instruction

1. For a start measure electromotive current on a current source, having connected terminals of the tester created for voltage measurement to source terminals. You will see result in the form of the digital value in volts displayed on the tester screen. Very often by the EMF of a source it is specified on it in advance. For example, 12 volts in the accumulator or 220 volts in the electric socket. Internal resistance is usually unknown.

2. Now calculate required internal resistance. Connect to a current source the consumer whose resistance will be known to you. Besides, use the resistor which resistance can be recognized by the special code, or having measured by a tester. Attach it to a source, and then check tension, having attached a tester to the resistor in parallel. Tension on the resistor will be obligatory less than the EMF of a source. Now calculate the internal resistance of a source of current. From EMF take away tension on the resistor, divide a difference into value of tension on the resistor. Now increase the received figure by resistance rezistorar= (EDS-U) • R/URezultat will be presented in Ohms.

3. Now it is necessary to find short circuit current. For this purpose EMF a source of current needs to be divided into the internal resistance of a source of current.Ikz = EMF/rÉÑºÒ½ýÔáÔ you receive in amperes.

4. This value allows to check short circuit for concrete, used by you, a current source. In any chain attached to a source, at achievement of the calculated size there will be a short circuit. In order that similar did not happen, establish in electrical circuits thermal or fuses. Safety locks break off a chain at excess of value of current which is equal to short circuit current.

Author: «MirrorInfo» Dream Team