According to Elder (1993) Bull Power reflects the Bulls' (who make money in a rising market) ability to push prices higher. It is calculated as the difference between the High price and an exponential moving average over a term you determine. Bull Power would be positive except in the presence of very strong bearish forces near the turning point of a bearish market

According to Elder, a trading signal is given when the exponential moving average is trending down and the Bull Power is positive but falling.

To confirm the signal, Elder uses Bull Power in conjunction with Bear power.

You may wish to add some type of Moving Average to this indicator's graph.

References

Elder, Dr A. (1993). Trading for a Living. Wiley.