# Help understanding Reactive Power

Discussion in 'Homework Help' started by veneficus5, Apr 22, 2011.

1. ### veneficus5 Thread Starter New Member

Mar 8, 2010
17
0
I'm not sure I understand what reactive power is. Does anyone have good links/advice?

My teacher said the power company will charge you for using reactive power, yet he also on another occasion said reactive power really isn't power so I don't have a very good grip on what's going on. I'm fine with the calculations, but I'd rather not memorize and isntead understand.

Thanks!

2. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
If a consumer's electrical load comprises both real & reactive power the electric current drawn from the supply authority's conductors accounts for both the real and reactive power.

While the current contribution from the reactive power serves no useful purpose for you as the consumer, the supply authority has to provide that current to you and this current produces heat energy losses in the current carrying conductors and transformer windings which form the power grid. This lost energy equates to a cost for the supply authority. The supply authority could elect to absorb that cost themselves or charge the end user for the cost. Obviously they choose the latter option.

Large consumers are therefore usually obliged to take steps to reduce their power costs by reducing their (unavoidable) reactive power current draw at their point of common connection to the power grid. Large consumers routinely install power factor correction (PFC) equipment to reduce their reactive power current draw and thereby reduce their power bills. The return on capital investment for the PFC installation is normally realized in an appropriate time frame consistent with their operations and bottom line.

3. ### veneficus5 Thread Starter New Member

Mar 8, 2010
17
0
very helpful. Thank you sir or ma'am