Step 9 for Compressed Air Analysis : Electrical Power Sizing, monitoring the energy performance of Compressors

There is many components in a compressed air system that consumes electrical power, namely compressors, air dryers and filters, valves and pressure regulators, chillers, fans and so on. Firstly, a basic understanding of Electrical Energy and power measurement is needed to ensure performance and efficiency of the compressed air system:

Real Power (P, kW) represents the actual power that is consumed by the system to do useful work, i.e. power effectively converted into mechanical energy in a compressor.
Reactive Power (Q, kVAR) is the power that does not do useful work, but is necessary to maintain inductive load in the system, commonly in compressors, motors and transformer to maintain their magnetic field (in which voltage leads current)
Apparent Power (S, kVA) is the total power that is supplied to the system, including both real power and reactive power, forming the power triangle relationship: S²=P²+Q² .
Power Factor (PF or impedance phase shift) is the ratio of real power to apparent power, indicating how efficiently electrical power is converted to useful work.
Active Energy (kWh) is the total real power P consumed over time, useful for quantifying electricity usage over time for billing purposes and tracking consumption trends.

With monitoring assigned to different machines in the system, common symptoms that can be gauged with power readings:

Low Power consumption: Compressor not operating at full capacity, power supply issue, motor failure or air leaks.
High Power consumption: Inefficient compressors, aging compressors, electrical faults, improper control settings (compressors idling). Excessive load will increase motor wear and tear and cause overloading due to high temperatures.
Low power factor PF: Wastage of reactive power due to unoptimized inductive loads, lack of power factor correction (PFC).
Fluctuating power: Intermittent load changes, Variable Frequency Drive (VFD) Instability, Harmonic disruption or other power quality issues.
Excessive cycling of compressors: Incorrect system pressure settings, improperly sized compressors, fluctuating air flow and demand. Do System optimization or add storage tanks to smooth out demand.

With these electrical issues identified, common measures include:

Proper maintenance with lubrication and cooling system sizing to prevent overheating, wear and tear.
Proper Load management and scheduling, incorporating VFDs with base load compressors to adapt to changing demands.
Power Quality Improvement with PFC equipment, harmonic filters, surge protectors and UPS systems.
Proper alarm controls for abnormal power usage indication.

Data from power readings are used in tandem with other control parameters such as pressure, flow, humidity and dewpoint to differentiate between machines electrical issues and other components such as pressure and piping sizing, clogged filters, leakages.

Besides routine inspections and maintenance, best practices including conducting energy audits (ISO 50001) real time monitoring and data logging in order to optimize energy usage and efficiency in compressed air systems.

CS Instruments provides power monitoring solutions, for stationary, mobile and clamp on solutions. Features included different sizing for current transformers, high accuracy class (IEC 62053-21 Class 1), high current application and lightweight flexibility via Rogowski coils.