Battery and Battery Charger Sizing Calculation

Station batteries play a very important role in a High voltage substation. It supplies the DC power to critical loads like Circuit breaker closing and tripping coils, Numerical relays, Master trip relay, Auxiliary relays, Substation automation systems, Alarm and Annunciation circuits, Substation hooters, bells, Indication lamps, Fire detection and alarm systems, DC emergency lighting etc. In case of failure of the normal AC supply, DC supply from the battery chargers are unavailable. During this period, the Batteries provide supply to these critical loads and keep the system safe and protected. Batteries can beare of different types - Lead acid conventional, Lead acid sealed maintenance free, Nickel Cadmium conventional, Nickel cadmium seal maintenance free etc.

The Battery sizing calculation is done as per IEEE 485 for Lead acid batteries and IEEE 1115 for Nickel cadmium batteries. The sizing calculation is done on the basis of the following loads :

1. Continuous load

2. Emergency lighting load

3. Momentary tripping load

4. Restoration load

The period for which the above loads will be applicable, play an important role in selection of AH rating of the battery.

The battery charger sizing (in A) is dependent on battery AH rating, discharge duration, continuous and emergency lighting load on battery.

Satcon has a very long history of preparing the Battery and Battery charger sizing calculation for various type of electrical systems like Substations, Industrial electrical network etc. Satcon has the latest ETAP software through which it is possible to undertake Battery sizing calculations for any Substation projects.