Our Western Watt Power Conditioning System
Typical Power Meter Hookup
Please refer to above drawing. The power company’s power meter measures the voltage (V) across the incoming lines and it measures the current (A) on the return line from the building. Since Power = Voltage * Current, it multiples these two measurements together to obtain a power measurement. It accumulates these measurements to produce a measurement of power consumed versus time.
For example: If one provides 120V at 10 Amps this is 1.2kW. If this is continuously applied for hour, this is 1.2 Kilowatt hour. If the voltage is increased to 130V and the current draw is maintained. 1.3 kW will be consumed in 1 hour.
Assume that an electric motor is rated at 120V. this means that if 120V is applied, the motor will produce the appropriate power to perform its designed function. If a voltage in excess of 120V is applied, unnecessary power will be delivered to the motor. This will result in excess, wasted power consumption.
Typical Power Meter Hookup with our Western Watt Power Conditioning System
The second drawing shows a typical installation of the power conditioner. The unit has the ability to temporarily store excess energy which is either smoothly provided to the motor when required, or returned to the far side of the current transformer. This prevents it from being recorded on the power meter.
The power conditioner also provides Power Factor Correction. An induction motor draws current from the supply that is made up of resistive components and inductive components.
The resistive components:
- Load current
- Loss current
And the inductive components are:
- Leakage reactance
- Magnetizing current
The current due to the leakage reactance is dependent on the total current drawn by the motor, but the magnetizing current is independent of the load on the motor. The magnetizing current will typically be between 20% and 60% of the rated full load current of the motor. The magnetizing current is the current that establishes the flux in the iron and is very necessary if the motor is going to operate. The Magnetizing current does not actually contribute to the actual work output of the motor. It is the catalyst that allows the motor to work properly. The magnetizing current and the leakage reactance can be considered passenger components of current that will not affect the power drawn by the motor, but will contribute to the power dissipated in the supply and distribution system. Take for example a motor with a current draw of 100 Amps and a power factor of 0.75. The resistive component of the current is 75 Amps and this is what the KWh meter measures. The higher current will result in an increase in distribution loss of (100 x 100) / (75 X 75) = 1.777 or 78% increase in the supply losses.
In the interest of reducing the losses in the distribution system, power factor correction is added to neutralize a portion of the magnetizing current of the motor. Typically, the corrected power factor will be 0.92 – 0.95. Some power retailers offer incentives for operating with power factor of better than 0.9, while others penalize consumers with a poor power factor. There are many ways that this is metered, bu the net result is that in order to reduce wasted energy in the distribution system, the consumer will be encouraged to apply power factor correction.
Power factor correction is achieved by the addition of capacitors in parallel with the connected motor circuits and can be applied at the starter, or applied at the switchboard or distribution panel. The resulting capacitive current is leading current and is used to cancel the lagging inductive current flowing from the supply.