Measurement Equipments

Power Meter

See what your compressors really draw, and how much of that energy actually turns into air.

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A panel-mounted power meter with a display reading volts, amps, kW and MWh

Product overview

Know the true energy cost of your compressed air

Our power meter measures the electrical energy your compressor, dryer or whole compressor room draws, and relates it to the air produced. It records active power (kW), accumulated energy (kWh), current, voltage, power factor and reactive power on each phase of a three-phase supply. Paired with a compressed air flow meter, it gives you specific power in kW per m³/min, or specific energy in kWh per m³: the efficiency figure of your air system.

Current sensors clamp around the supply conductors and voltage leads connect to the same phases. The meter samples both thousands of times a second and multiplies them to give true active power, including the effect of phase shift and harmonic distortion. That matters in a compressor room, where unloaded motors run at low power factor and variable speed drives draw distorted current.

Use it for a temporary audit of one to several weeks, clamped around live cables without disconnecting the compressor, or for continuous monitoring that feeds your energy management system. A 75 kW compressor running 8,000 hours a year at an average input of 70 kW consumes 560,000 kWh, and a measured load profile shows how much of that makes air and how much goes on unloaded running, blowdown and leaks.

A flexible clamp-on current coil with its cable
  • kW per m³/minSpecific power, the efficiency figure of your air system
  • 560,000 kWhA year for a 75 kW compressor averaging 70 kW over 8,000 hours
  • 25–35 %Of full-load power commonly drawn unloaded by oil-injected screw compressors
  • About 7 %More compressor energy for each extra 1 bar of discharge pressure

Benefits

The problems it solves

Electricity is the dominant cost of owning a compressor, yet most plants never measure it. Here is what that hides, and how the meter brings it into view.

  • Current readings mislead

    The problem

    Panel ammeters show current, not power. When a compressor unloads, its power factor falls steeply, so current overstates what it consumes.

    How it solves it

    The meter measures true active power: a 90 kW compressor drawing 80 A unloaded at 0.40 power factor uses 22 kW, only about 25 % of its loaded power, though its current is still 55 % of loaded current.

  • Hidden unloaded running

    The problem

    A fixed-speed compressor running unloaded still drives its motor, air end and fan while delivering no air.

    How it solves it

    The power trace separates loaded, unloaded, blowdown, standby and stopped states, and shows the hours and energy spent in each.

  • Leaks with no price

    The problem

    Leak repair competes with other projects for maintenance time and budget.

    How it solves it

    Power drawn when production stops puts a figure on it: a compressor room drawing 40 kW through a 48-hour weekend uses 1,920 kWh, roughly 100,000 kWh a year, on leaks and unloaded running.

  • Nameplates are not bills

    The problem

    A motor rating shows shaft output capacity, not input. Actual input varies with discharge pressure, inlet temperature, part load, fan duty and motor efficiency.

    How it solves it

    Measured kW and kWh express your real consumption in energy and money per shift, day and year.

  • Savings you cannot prove

    The problem

    Without a measured baseline, the savings from a new compressor, drive or controller cannot be calculated with confidence, and achieved savings cannot be proven.

    How it solves it

    Before-and-after measurements by the same method prove the result of leak repairs, pressure reductions and equipment changes.

  • Efficiency that slips

    The problem

    Air-end wear, fouled coolers, blocked inlet filters and failing unloading valves all make your compressors less efficient.

    How it solves it

    A gradual rise in specific power at the same pressure and flow points to them early.

Where it’s used

Wherever compressors run up the bill

Any plant where compressors are among the largest electrical loads, and anyone who needs to prove what an improvement has saved.

  • Robots welding a car body on an assembly line

    Automotive and engineering

    Large multi-compressor rooms supplying assembly tools, paint shops and robots across several shifts.

  • A row of yarn winding machines in a textile mill

    Textiles

    Air-jet weaving looms and spinning machines that consume high air volumes continuously.

  • Blue plastic bottle caps in a moulded tray

    Plastics and packaging

    PET blow moulding compressors at 30–40 bar g, among the largest electrical loads in the plant.

  • Wine bottles moving along a bottling line

    Food, beverage and pharmaceuticals

    Energy data tracked together with air quality compliance data.

  • A worker pouring concrete over steel reinforcement

    Cement and glass

    Compressors and blowers running continuously for conveying and combustion duties.

  • Molten metal pouring from a ladle in a foundry

    Steel and mining

    Compressors, blowers and vacuum pumps running continuously for process duties.

Also compressed air energy assessments to ISO 11011:2013, ISO 50001 energy management, measurement and verification of savings, compressor acceptance testing to ISO 1217:2009, hospital medical air and vacuum plants, nitrogen and oxygen generation, and leak surveys.

How it works

Clamp, measure, compare

The meter reads the current and voltage on every phase, multiplies them into true power, and sets that against the air your compressor delivers.

How a compressor power meter works: current clamps and fused voltage leads on each phase of the compressor supply feed the power meter, which samples voltage and current together thousands of times a second and multiplies them into true active power and energy. A flow meter and pressure transmitter on the discharge header feed the same data logger, which divides power by flow to give specific power in kW per m³/min. L1L2L3 M FT PT kW · kWh · PF 8024kW kW ÷ m³/min Distribution boardStarter or driveClampsVoltage leads Power meter v × i, thousands of times/s kWh = Σ kW × Δt Data logger MotorAir endReceiverDryerFlow meterPressureTo networkevery 1–10 s 0.1 kWh/m³ = 6 kW per m³/min 12345 Supply current, L1 to L3Voltage leadsCurrent, flow and pressure signalsData to the loggerCompressed airPlant equipment

  1. 1. Clamp onCurrent sensors clamp around the three supply conductors upstream of the starter or drive, with no cable disconnected and no production stop. Fused voltage leads connect to the same phases.

  2. 2. Sample and multiplyThe meter samples voltage and current on every channel at the same instant, thousands of times a second, and averages their product. That gives true active power, phase shift and harmonics included, summed across all three phases.

  3. 3. Power over timeAdding up power over time gives energy in kWh per interval, shift or day. For a compressor drawing 80 kW loaded and 24 kW unloaded, the stepped trace shows exactly how long it spends delivering no air.

  4. 4. Air alongsideA flow meter and pressure transmitter on the discharge header record the air your plant actually receives, logged every 1 to 10 seconds on the same time base as the power.

  5. 5. Specific powerDividing power by flow gives specific power in kW per m³/min, the efficiency figure of your system. A specific energy of 0.1 kWh per m³ equals a specific power of 6 kW per m³/min.

Specific power is meaningful only with the pressure and the flow reference stated.

Get the full details

Our brochure covers it in detail, and our questionnaire tells us what we need to recommend the right one for your plant.

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