Polarity

Updated: Nov 27, 2020

Polarity is a term used in industries and fields that involve electricity. There are two types of poles: positive (+) and negative (−). It represents the electrical potential at the ends of a circuit. A battery has a positive terminal (+ pole) and a negative terminal (− pole).


In the context of electrical installations, a polarity test is used to confirm the correct connection of the line and neutral conductors. Similarly, it's important to confirm that switches are located in the line conductor, not the neutral conductor. Electric polarity applies to direct current electricity, the type delivered by batteries. Batteries have two terminals from and to which the electric current flows.


For electricity installations, a #polarity test is used to confirm the correct connection of the line and neutral conductors. It is important to confirm that switches are located in the line conductor, not the neutral conductor.


What is the electrical polarity?

Electrical polarity is present in every circuit where electrons flow from the negative pole to the positive pole and the current flows from the positive to the negative terminal.



a) In a DC circuit, the electrons flow in one direction only. One pole is always negative and the other is always positive. The #equipment in this is polar sensitive.


b) In an alternating circuit(AC), the two poles alternate between negative and positive terminals. The direction of the electron flow continually reverses. It happens almost 60 times per minute. The electricity flows back and forth to form a sine wave.


In comparison, AC current is used over DC current in many places because the voltage can be changed easily making it more suitable and convenient for long-distance transmission. Direct current (DC) flows in one direction, resulting in a constant polarity. Alternating current (AC) flows half the time in one direction and half the time in the other, changing its polarity 120 times per second with the 60-hertz current.


Polarity testing-

A polarity test is used to confirm the correct connection of the line and neutral conductors. In an ac supply, a polarity test is done to ensure that the line and neutral conductors are connected the correct way. The purpose of a polarity test is to ensure that all single pole devices (fuses, switches, and circuit breakers) are connected in the phase conductor only.


It is a test that creates a circuit using the #phase conductor and the single pole device, breaking the circuit when the device is being operated, where the reading on the instrument l changes, confirming that that device must be connected in the phase conductor.


This test verifies that all the switches installed in the system are connected in the current-carrying conductor and not in neutral. For example, if we isolate or switch the neutral of a circuit via a single-pole circuit breaker or switch, it appears that the circuit is dead where in fact it is still live. If the polarity is not correctly determined there may be a risk of electric shock during maintenance procedures.


Methods of Polarity testing-


a) Polarity by visual inspection:

By using our knowledge, we can establish the correct termination of cables relating to core colors. Checking polarity visually during the process of installation, especially in cases where checking by testing is impractical.


b) Polarity by continuity testing:

If the #visual inspection is not possible, we can use a low-resistance ohmmeter for this test. When we test radial and ring final circuits, part of the process is to test and inspect the polarity of fixed equipment and socket outlets.

Steps:

  1. Switch off the circuit breaker supplying the circuit.

  2. From the specific circuit, put a temporary link that will connect the line conductor and the CPC or any equipotential bonding conductors. It will serve as a testing point for convenience

  3. Conduct continuity testing by placing the test leads across the line conductor and the nearest  CPC or any exposed #conductive parts of the circuit.

  4. If the instrument shows zero reading (with continuity sound) then the switch is connected properly to the line conductor.

  5. If the instrument shows some significant ohmic value then the switch is not connected to the line conductor. Interchange the connections to fix the problem.


Reversed polarity-

When the polarity is reversed, it means that the neutral wire is connected to where the hot wire is supposed to be. There is always electricity flowing out of an outlet with reversed polarity, even if an appliance is supposed to be off.


Reversed polarity on an electrical outlet is dangerous. If you accidentally reverse these wires the device you plug into the receptacle may "work" but it is unsafe and risks a short circuit, shock, or fire. Avoiding reversed polarity is important because, with reversed polarity, a shock hazard can be created in certain situations.


Difference Between Straight Polarity and Reverse Polarity in Arc Welding


Arc welding power sources can supply either AC or DC or both forms of current type. In arc welding, base metals are related to one terminal and the electrode is attached to a different terminal. Under the presence of enough capacity difference, the non-stop flow of electrons among them via a small hole constitutes the arc (high source of heat in arc welding). Based on the connections, DC electricity can offer polarities, as furnished below:


a) Direct Current Straight Polarity (DCSP) When the electrode is attached to the poor terminal of the electricity supply and base metals are related to the positive terminal.

b) Direct Current Reverse Polarity (DCRP)

When base metals are related to the poor terminal of the electricity supply and electrode

is connected with the positive terminal.


See Also:

  1. Flip-Flop

  2. Quality Factor

  3. Analog to Digital Conversion


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