What we have done, and what we are doing
to help reduce energy consumption

Part 8: TOTAL ENERGY COSTS

| Real Power | Power Factor | Demand Charges | Industry Responsibility |
| Reliance's Role | Conclusion | Appendix |

There are three basic components of industrial power cost: cost of Real Power used; power factor penalties and demand charges. To understand these three charges and how they are determined, a review of the power vector diagram (Figure 27) identifies each component of electrical energy and its corresponding energy charge.

Figure 27
Electrical Power Vector

Real Power

The Real Power-KW is the energy consumed by the load. Real Power-KW is measured by a watt/hour meter and is billed at a given rate ($/KW-HR). It is the Real Power component that performs the useful work and which is affected by motor efficiency.

Power Factor

Power factor is the ratio of Real Power-KW to Total KVA. Total KVA is the vector sum of the Real Power and reactive KVAR. Reactive power is required to support the magnetic field of the induction motor. Although Reactive KVAR performs no actual work, an electric utility must maintain an electrical distribution system, (i.e., power transformers, transmission lines, etc.) to accommodate this additional electrical energy. To recoup this cost burden, utilities may pass this cost on to industrial customers in the form of a power factor penalty, for power factor below a certain value.

Power factors in industrial plants are usually low due to the inductive or reactive nature of induction motors, transformers, lighting and certain other industrial process equipment. Low power factor is costly, and requires an electric utility to transmit more Total KVA than would be required with an improved power factor.

Low power factor also reduces the amount of Real Power that a plant’s electrical distribution system can handle, and increased line currents will increase losses in a plant’s distribution system.

A method to improve power factor, that is typically expensive, is to use a unity or leading power factor synchronous motor or generator in the power system. A less expensive method is to connect properly sized capacitors to the motor supply line. In most cases, the use of capacitors with induction motors provides lower first cost and reduced maintenance expense. Figure 28 graphically shows how the Total KVA vector approaches the size of the real power vector as reactive KVAR is reduced by corrective capacitors. Because of Power Factor correction, less power need be generated and distributed to deliver the same amount of useful energy to the motor.

Figure 28
Electrical Power Vector

Just as the efficiency of an induction motor may be reduced as its load decreases, the same is true for the power factor only at a faster rate of decline. A typical 10 HP, 1800 RPM, 3-phase, Design B Motor with a full-load power factor of about 80 percent decreases to about 65 percent as half-load.

Therefore, it is important not to oversize motors. Select the right size motor for the right job. Figure 29 shows that the correction of power factor by the addition of capacitors not only improves the overall power factor but also minimizes the falloff in power factor with reduced load.

Figure 29

Demand Charges

The third energy Component affecting cost is demand charge and is based on the peak or maximum power consumed or demanded by an industrial customer during a specified time interval. Because peak power demands may require an electric utility to increase generating equipment capacity, a penalty is assessed when demand exceeds a certain level. This energy demand is measured by a demand meter and a multiplier is applied to the Real Power-KW consumed.

Industrial plants with varying load requirements may be able to affect demand charges by: 1) load cycling - stagger the starting and use of all electrical equipment, and discontinue use during peak power intervals, and 2) use of either electrical or mechanical "soft start" hardware which limits power in rush and permits a gradual increase in power demand.

INDUSTRY RESPONSIBILITY - GOVERNMENT INVOLVEMENT

Energy savings is a key policy issue and the federal government is anxious to affect reductions in energy usage as quickly and efficiently as possible. The federal government can get involved in the issue of motor efficiency and energy usage by encouraging the purchase of high efficiency motors and by legislative action.

Of all the federal government options, the FEA study report favored educating and influencing motor users to purchase high efficiency motors. The FEA study concluded that increasing energy costs will create increased market demand for high efficiency motors and that manufacturers will be stimulated to produce and promote them.

The question that remains is, who is going to take the initiative to inform and educate motor buyers? Reliance believes that industry can accomplish this task to everyone’s satisfaction with a concerted effort on the part of motor manufacturers and professional and trade associations to provide information to evaluate payback of energy efficient motors.

Industry standards are now in place. NEMA has adopted an unambiguous standardized method for testing (MG 1-12.58.1), efficiency labeling (MG 1-12.59), defining minimum efficiencies for motors which are labeled "Energy Efficient" (Table MG 1-12-8). See Appendix 1 for these tables. The efficiency labeling standard requires that NEMA Design A, B or C, 1-125 HP motors be labeled with the NEMA nominal efficiency. Furthermore, NEMA standards require the use of the standardized test method, based on lEEE 112, method B.

Motor end-users should take advantage of these in-place standards and should specify products that meet NEMA standards, thereby requiring that the motor supplier comply with these efficiency labeling and test standards. This will provide the end users with a common basis to compare and evaluate energy efficient motor alternates.

Reliance believes that government involvement in motor efficiency should be limited to its cooperation with professional and trade associations. However, where government intervention appears inevitable, Reliance is committed to working with the government through these professional and trade associations.

RELIANCE ELECTRIC’S ROLE —
PRESENT AND FUTURE

To date, Reliance has been involved in informing motor users relative to motor efficiency and energy savings. Reliance was the first motor manufacturer to implement the NEMA efficiency Index Labeling program and to offer a modifiable, high performance motor design. In addition, Reliance has introduced energy efficient products, such as a highly efficient permanent magnet rotor (PMR) synchronous motor, as well as the DutyMaster XE line of energy efficient motors, and continues to work with OEM’s in the application of motors for specific purposes.

As a responsible industrial motor manufacturer, Reliance is committed to providing consistent, representative efficiency data for motor users to help evaluate our motor product offerings that allows them to select the most efficient motors for their applications in terms of energy consumption and related energy costs. In view of that commitment, Reliance continues to stress the need for standardizing and improving test methods.

Reliance is also investing in considerable manufacturing and engineering technology to advance processes and methods that will improve motor efficiency at minimal cost. Advanced engineering efforts are continuing to optimize motor design, including material selection, that will yield maximum efficiency performance.

As technology advances and motor users become more informed in the proper application of high efficiency motors, Reliance will respond to the growing demand with new, improved energy efficient motor products to meet customers needs.

Conclusion

We hope this paper has helped to increase your knowledge and ability to apply energy efficient motors. Reliance would like to remind you there are many other ways to conserve energy and your investigations should not stop with motors.

APPENDIX 1

TESTS AND PERFORMANCE-AC

NOTE: Table 12–6C also represents the Efficiencies proposed in the 1992 U.S. Energy Policy and Conservation Act.

Document B7087.5