Station Battery or DC Supply Arrangement
Station batteries supply energy to operate protection equipment like as breakers and other control, alarm and indicating equipment. The station batteries are a source for operating DC control system equipment during system disturbances and outages. During normal conditions the rectifier provides the required DC supply. Therefore, to take care of rectifier failure, a storage battery of adequate capacity is given to meet the DC requirements.
Generally, in a 33/11 kV substation, the DC system is of 30 cells consisting of 15 lead acid storage batteries or Nickel-Cadmium batteries. The battery is linked in parallel along with a constant voltage charger and critical load circuits. The charger maintains the needed voltage at battery terminal and supplies the generally connected loads. This sustains the battery in fully charged condition. The correct size battery charger has to be chosen for the intended application.