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Summary

New Variable Speed Drives

Motor Drives: New Variable Speed vs. Constant Speed

Provide efficient fluid flow control in new and retrofit applications.

Synopsis:

Adjustable speed drives (ASDs) are in common use throughout the nation. Low- and medium-voltage, pulse-width, modulated ASDs are widely available from multiple manufacturers and in all size ranges. The 1998 "Industrial Electric Motor Systems Market Opportunities Assessment," indicated that about 8.8% of all motor systems in the manufacturing sector employed ASD speed control.  This number has increased significantly in the last 14 years.

Vector control (positioning control) for drives is also available and has been employed in conveyor and elevator applications. ASDs are now built into air compressor cabinets and variable speed trim compressors and are available from many manufacturers. ASDs have also been optimized for constant torque applications such as elevators.

From 18% to 25% of motor energy use in manufacturing could cost-effectively be equipped with ASDs.  Barriers to additional drive installations include the need for additional education for plant staff, metering to understand process requirements and the short 1- to 3-year simple paybacks required by industrial plant managers. ASDs are being employed to more closely follow variable system or process flow requirements, such as changing ventilation rates and filter baghouse flows to correspond to various requirements during an electric arc furnace’s melting, charging, and tipping processes.

ASDs work as advertised and early problems with premature motor failures (due to voltage overshoot and bearing failures due to shaft current formation) have been solved using load reactors, dV/dt filters, shaft grounding brushes and insulated motor bearings and couplings.

Energy savings of 20% to 50% are typical in good ASD applications.

Energy Savings: 31%
Energy Savings Rating: Approved Measure  What's this?
LevelStatusDescription
1Concept not validatedClaims of energy savings may not be credible due to lack of documentation or validation by unbiased experts.
2Concept validated:An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles.
3Limited assessmentAn unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline.
4Extensive assessmentAdditional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions.
5Comprehensive analysisResults of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications.
6Approved measureProtocols for technology application are established and approved.

Status:

Details

New Variable Speed Drives

Motor Drives: New Variable Speed vs. Constant Speed

Provide efficient fluid flow control in new and retrofit applications.
Item ID: 91
Sector: Commercial, Industrial
Energy System: Motors & Drives--Drives

Synopsis:

Adjustable speed drives (ASDs) are in common use throughout the nation. Low- and medium-voltage, pulse-width, modulated ASDs are widely available from multiple manufacturers and in all size ranges. The 1998 "Industrial Electric Motor Systems Market Opportunities Assessment," indicated that about 8.8% of all motor systems in the manufacturing sector employed ASD speed control.  This number has increased significantly in the last 14 years.

Vector control (positioning control) for drives is also available and has been employed in conveyor and elevator applications. ASDs are now built into air compressor cabinets and variable speed trim compressors and are available from many manufacturers. ASDs have also been optimized for constant torque applications such as elevators.

From 18% to 25% of motor energy use in manufacturing could cost-effectively be equipped with ASDs.  Barriers to additional drive installations include the need for additional education for plant staff, metering to understand process requirements and the short 1- to 3-year simple paybacks required by industrial plant managers. ASDs are being employed to more closely follow variable system or process flow requirements, such as changing ventilation rates and filter baghouse flows to correspond to various requirements during an electric arc furnace’s melting, charging, and tipping processes.

ASDs work as advertised and early problems with premature motor failures (due to voltage overshoot and bearing failures due to shaft current formation) have been solved using load reactors, dV/dt filters, shaft grounding brushes and insulated motor bearings and couplings.

Energy savings of 20% to 50% are typical in good ASD applications.

Baseline Example:

Baseline Description: Constant Speed Motor-Driven Systems
Baseline Energy Use: 2923 kWh per year per hp

Comments:

The baseline is a 200 hp boiler forced draft fan motor operating at constant speed at a lumber drying kiln. It uses 584,752 kWh/year according to a study performed by the Washington State University Energy Program.

Manufacturer's Energy Savings Claims: Currently no data available.
Best Estimate of Energy Savings:

"Typical" Savings: 31%
Energy Savings Reliability: 6 - Approved Measure

Comments:

Energy Use of Emerging Technology:
2,016.9 kWh per hp per year What's this?

Energy Use of an Emerging Technology is based upon the following algorithm.

Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))

Technical Potential:
Units: hp
Currently no data available.
First Cost: Currently no data available.

Cost Effectiveness:

Simple payback, new construction (years): N/A

Simple payback, retrofit (years): N/A

What's this?

Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.

Reference and Citations:

Rank & Scores

New Variable Speed Drives

There is no TAG available for this technology.
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