ANALYSIS PARTIAL DISCHARGE (PD)

 

Partial Discharge Analysis - Partial Discharge Analysis, is a step to diagnose the condition of an electrical equipment against the possibility of an electric spark caused by an air pocket confined in the insulation of the electrical equipment. Partial discharge measurements can be carried out continuously online, or periodically, so that from the measurement results, the condition of electrical equipment that requires maintenance can be analyzed.

For each material (material), besides having its tensile strength characteristics, each material also has a dielectric strength which indicates the electrical intensity required for current to flow in the material.

Commonly known insulating materials such as epoxy, polyester, and polyethylene have very high dielectric strength. In contrast, air has relatively low dielectric strength. An electric jump or spark in the air (breakdown voltage) can create a short circuit, and for electrical equipment this occurs in air pockets trapped in the insulation of the conducting winding. So that the measurement of partial discharge is actually a measurement of the electric jump in the air bag.

 

In any electrical equipment, manufacturing defects or operational problems can always occur due to failure of the original material. Electrical insulation in electric machines, such as motors, generators or transformers, is susceptible to thermal stress, chemical attack, and the movement of windings in the equipment due to vibration factors.

In all cases, the stress on the insulated winding can attenuate the bonding properties of the epoxy, resin or polyester material that coats and protects the coils. This can cause air pockets to develop in the coils. The emergence of a partial discharge in the air bag, in addition to indicating that the insulation capacity has begun to decrease and that air pockets have begun to appear, it can also speed up the process of damage to the equipment.