The primary regulation attempts to restore the balance between generation and load for both active and reactive power. It operates with no consideration for the cause or location of the initial imbalance. In some cases fast load shedding (described later) is necessary in order to enable the balance to be restored. Primary regulation can be implemented in several manners - it is the responsibility of the power system engineer to determine which mode is correct. The goal of primary regulation response should be to keep the frequency within ±0,5Hz and the voltage within ±5% after a disturbance has occurred. The frequency steady-state error is less than 150mHz.