Energy Savers

Technologies

Electrical Energy Savers tend to come in a number of formats, but most of the schemes promoted today tend to fall into one of three categories:

• 1. Nola "Power Factor Controllers"
• 2. Power Factor Correction
• 3. Voltage Regulators

Nola "Power Factor Controllers"

The Nola type Power Factor Controller is a system originally developed by Frank Nola of NASA as a means of reducing the iron loss on very small induction motors when operating under light load.
The principle of operation is simple, induction motors have three major sources of loss, copper loss, iron loss and slip loss.
The copper loss is equal to the square of the current times the stator resistance and increases with shaft load on the motor. The copper loss is lowest at light load.
The iron loss is a function of the flux in the iron. The flux is dependent on the applied voltage. The iron loss is independent of the load on the motor.
The slip losses are a function of the amount of slip and the shaft torque of the motor.
The Nola controllers operate by reducing the voltage applied to the motor when the motor efficiency is low, thereby reducing the iron loss and improving the operating efficiency of the motor. The power factor of the motor tends to fall as the motor efficiency falls. The Nola controllers monitor the operating power factor of the motor and compare this with a reference power factor. When the power factor is below the reference, they reduce the voltage until the power factor rises to equal the reference. If the load on the motor is increased, the power factor increases and the voltage is raised.
The reduced voltage reduces the magnetizing current and the iron loss. This will reduce the current into the motor provided that the load current is less than the magnetizing current.
Small single phase motors have a high iron loss per KW and can benefit from the application of this technology. Larger three phase motors have a very low iron loss per KW and any gains are very limited.
Nola Power Factor Controllers

Power Factor Correction

Inductive loads such as transformers, welders and induction motors draw work current and magnetizing current from the supply. The magnetizing current is 90 degrees out of phase with the work current and does not contribute to the actual work done, but does increase the current flowing from the supply.
Magnetizing current does not register on any power metering because it does not contribute to the KW absorbed by the load. The increased current due to the inductive current increases the copper losses in the supply, and the losses in the transformers and transmission equipment.
Power factor correction effectively neutralizes the magnetizing current flowing in the supply, reducing the total supply current and reducing the supply losses. The power factor correction does not alter the current flowing into the equipment and does not alter the KW used.
Power factor correction must match the reactive current in the load, too much correction will increase the reactive current as will too little correction.
Power Factor

Voltage Regulators

The energy consumed by resistive loads is proportional to the square of the applied voltage. If the applied voltage is higher than the nominal voltage of the load, it will absorb higher than design power and produce more than deign heat.
In an uncontrolled environment, this could result in additional heat losses. In controlled environments where the output is monitored and controlled thermostatically, the peak load may be higher, but the average power will remain the same. Lamps will produce a higher output at the higher voltage. If the lighting has been designed correctly at the nominal voltage, then excessive light is produced at an elevated voltage and energy is wasted.
Loaded motors will draw a higher iron loss and a lower copper loss at elevated voltages, the differences being very small, so little if anything will be gained by voltage control of motors unless the voltage is significantly higher than the nominal voltage.

Internal Links

Nola Power Factor Controllers
Power Factor

External Links

Nola Energy Savers are they a sham?
Power Factor