Complex sentence: There can be problems detecting standby power with appliances that use much power in standby mode (e.g. plasma televisions) and are therefore not detected and do not turn off in the desired way.
Split into simpler sentences: There can be problems detecting standby power with appliances that use alot of power in standby mode (eg. plasma televisions). These consume alot of power in standby mode and are therefore not detected and do not turn off in the desired way.