CW240 Precision Power Clamp-on Meter (obsolete)
Realization of Power & Power Quality Management

Get a view of energy consumption, improve productivity, discover electrical power waste and detect voltage fluctuations with the CW240. Power Quantity Measurement: For Power-Saving Diagnosis and Data Collection
Replaced by CW500

Yokogawa CW240 Clamp-on Power Analyzers
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  • Simultaneous measurement of instantaneous value, electric energy, demand, harmonics and voltage fluctuation.
  • Simultaneous measurement of loads in 4 systems of up to 1P2W
  • Simultaneous measurement of loads in 2 systems of up to 1P/3P3W
  • Data saving interval can be set from 1 waveform (for instantaneous measurement) to 1 hour
  • Measure up to 50th order harmonics
  • 4ch leakage current measurement using newly released clamp probe 96036
  • Long time data logging by using compact flash memory
  • 2ch analog input (Optional)
  • Equipped with 4ch analog output (recorder output)
  • AC adaptor for power supply. NiMH rechargeable battery and alkaline battery for backup
  • IIII [+] more


    • Get a view of energy consumption

      It is essential to measure energy and manage consumption of each sector such as facility and production line for your energy saving activities and to minimize loss.
    • Contribute for improving productivity

      Constantly analyze productivity by managing unit consumption. Managing voltage, current, electric power and power factor makes for good maintenance of production facility.
      Moreover, you can check operation management loss and enhance productivity.
    • Discover of electric power waste

      Measure and collect data of electric power consumption by short period. The CW240 can figure out load of production process, and has the ability to check wasteful time and current flow of standby load current.
    • Detect voltage fluctuation

      When trouble occurs on supply side of electric power, instantaneous voltage drop can affect quality of produced goods at the factory. The CW240 is useful for collecting data such as voltage fluctuation to prevent such problems.


  • Investigation into Energy Saving at Factories and Buildings
  • Power Quantity Measurement: For Power-Saving Diagnosis and Data Collection
  • Discovers Failures in Power Supply Lines
  • Demand Measurement: For Review and Investigation on Contract Demand
  • Energy Saving and Maintenance for Electric Equipment at Factories and Buildings
  • Power Supply Quality Check


The CW240 power meter is a complete tool for enhancing energy efficiency, finding areas for improvement and assessing equipment lifecycles. The meter provides in-depth information on how an item of equipment, an area of a plant or a complete facility is operating that goes beyond simply measuring power usage.

By using the supplied clamp-on components and probes, users can better determine maintenance, repair and replacement schedules for equipment such as transformers and motors. Information is provided with respect to load factors and demand factors, as well as current/voltage fluctuations at motor start-up.
  • Literature
  • Specifications
  • Applications
Literature and Technical Information
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Test and Measurement

++ CW240 Clamp-on Power Analyzer | Brochure (1 MB)
Model: Yokogawa CW240 Series Power Clamp-on Meter
Inputs Resistive potential division Clamp detection
Rated value
150.0 V
300.0 V
600.0 V
1000 V
Varies with the clamp and range used.
96036 (2A) 200.0/500.0mA/1.000/2.000A
96033 (50A) 5.000/10.00/20.00/50.00 A
96030 (200A) 20.00/50.00/100.0/200.0 A
96031 (500A) 50.00/100.0/200.0/500.0 A
96032 (1000A) 200.0/500.0 A/1.000 kA
(3000A range) 300.0/750.0 A/1.500/3.000 kA
(2000A range) 200.0/500.0 A/1.000/2.000 kA
(1000A range) 100.0/200.0/500.0 A/1.000 kA
(3000A range) 300.0/750.0 A/1.500/3.000 kA
(300A range) 30.00/75.00/150.0/300.0 A
Phase to be
Single-phase 2-wire, single-phase 3-wire, single-phase 3-wire 3-current (current in neutral line),
three-phase 3-wire 2-current (2-power meter method), Three-phase 3-wire 3-current (3-power meter method), three-phase 4-wire,
three-phase 4-wire 4-current (current in neutral line), Scott connection (three-phase 3-wire + single-phase 3-wire)
Number of systems
to be measured:
With the same voltage
Single-phase 2-wire: 4 systems, single-phase 3-wire: 2 systems, three-phase 3-wire 2-
current: 2 systems
Input resistance: Approx. 1.3MΩ Approx. 100KΩ (CW240 main unit)
Maximum allowed
input (continuous):
1000 Vrms 96036 (2A) 20Arms
96033 (50A) 130Arms
96030 (200A) 250Arms
96031 (500A) 625Arms
96032 (1000A) 700Arms
(3000A range) 2400 Arms (3600 Arms for 10 minutes)
(2,000A range) 2400Arms
(1000A range) 1200 Arms
(3000A range) 3600 Arms
(300A range) 360 Arms
A/D converter: Voltage/current input simultaneous conversion, PLL synchronized 128 samples/period, 16-bit resolution
Input System: Single-phase 2-wire to 3-phase 4-wire Measurement Functions: Voltage, Current, Frequency, Active power, Reactive power, Power factor, Active electric energy, Regenerative electric energy, Reactive electric energy, Demand, Harmonics, Voltage fluctuation, Waveform.Viewer Software

|||| Click to View Measurement Specifications

Measurement Functions
Item Voltage Current / Active power / Reactive power (reactive power meter method is used)
Method: Digital sampling
Frequency range: 45 to 65Hz (Measurement element is selected from U1, U2 and U3)
Crest Factor: Rated input: 3 (however, 1.8 when 1000V range is used)
Accuracy: ±0.2%rdg ±0.1%rng. 96030, 96031, 96033, 96036 [±0.6%rdg.±0.4%rng.] 96032, 96034, 96035 [±1.0%rdg.±0.8%rng.]
Power FactorInfluence: _____________ 96030 [±1.0%rng (45 to 65Hz, power factor =±0.5)] Other than 96030 [±2.0%rng (45 to 65Hz, power factor =±0.5)]
Reactive Factor
_____________ 96030 [±1.0%rng. (45 to 65Hz, reactive factor =±0.5)] Other than 96030 [±2.0%rng (45 to 65Hz, reactive factor =±0.5)]
Active Input Range: 5 to 110% of each range (Max. 100% in the case of 1000V range)
Display Range: Voltage / current: 0.4 to 130% of each range
(Zero suppression when below 0.4% of the range)
Power (active, reactive, apparent): 0 to 130% of each range
(Zero suppression when below 0.17% of the range rating).
Harmonic level: 0 to 130% of each range
Frequency: 40 to 70Hz
Temperature Coefficient: ±0.03%rng/°C ±0.05%rng/°C

|||| Click to View Specifications (cnt’d)

  Active power, reactive power, apparent power, power factor and phase angle are measured for each phase.
The average, maximum and minimum values of those obtained during integrating measurement are calculated.
Display: 5.7-inch STN monochrome LCD display (320 dots x 240 dots) with backlight
Items other than power quantity: 4 digits
Power quantity: 6 digits
Frequency: 45 to 65 Hz
Power Quantity: Active power quantity, regenerative power quantity, reactive power quantity (lead/lag)
Measurement accuracy of active power and reactive power ±1dgt (When STANDARD is selected for display digits)
Demand Measurement: Active power (consumption), reactive power (lagging), power factor: Demand value within the interval time
Active power quantity (consumption, regeneration), reactive power quantity (lagging), leading: Power quantity within the interval time
Maximum demand (consumption power demand) required since the start of integrating measurement and the time it occur
Measurement accuracy of active power and reactive power ±1dgt
Harmonic Measurement: PLL synchronization
Fundamental wave frequency 45 to 65 Hz
1st to 50th
Waveform Measurement: Selectable from voltage/current waveform of same phase, all voltage waveforms, and all current waveforms.
Voltage Fluctuation: Voltage dip, voltage swell, instantaneous power failure
Detected based on voltage rms of one waveform.
Can be set in percentage in relation to the reference voltage. Same as voltage rms accuracy
Time length during which the threshold is exceeded
Occurrence date (year, month, day), voltage rms, detection
  Electrical specifications: EIA RS-232
Synchronization: system Asynchronous communication
Baud rates: 1200/2400/9600/19200/38400 bps
Connector: D-sub 9-pin
Power supply: AC adapter (standard accessory), 100 to 240 VAC, 50/60Hz
Power Consumption: Main unit: Approx. 10W (normal operation), approx. 20W (during charging of NiMH battery pack)
AC adaptor: Approx. 30VA (normal operation), approx. 60VA (during charging of NiMH battery pack)
Operating Temperature: 5 to 40°C, 5 to 80%RH (no condensation)
Storage Temperature: 20 to 60°C, 90%RH (no condensation)
Dimensions: Approx. 206(W)x184(H)x65(D)mm (excluding projecting parts)
Weight: Approx. 1.2 kg (without batteries)

Power Investigation Improves power Efficiency Through Detailed Data Collection


Measurement of Instantaneous Value

  • Measurement:Voltage/current/electric power (active, reactive, apparent)/power factor/phase angle of each phase, average/minimum/maximum values of each measurement element.
  • Data Collection:1/2/5/10/15/30 seconds, 1/2/5/10/15/30/60 minutes One cycle (waveform), 100/200/500 ms (short time interval)

The CW240 can be used to carry out investigation regarding renewal of electric equipment such as transformers in building, check load factors and demand factors, and to check current/voltage fluctuation at motor start-up.

Power Quantity Measurement: For Power-Saving Diagnosis and Data Collection for ISO14001

  • Active power quantity, regenerative power quantity, reactive power quantity (leading/lagging)
  • 1/2/5/10/15/30 seconds, 1/2/5/10/15/30/60 minutes

The CW240 can measure and display the power quantity consumed up to the specified time (from the start of integration until the end).

Demand Measurement: For Review and Investigation on Contract Demand

  • Maximum power demand required since the start of logging measurement and the time it occurs
  • Active power, reactive power (lag), power factor
  • Active power quantity (consumption, regeneration), reactive power quantity (lagging/leading)

Normally, the demand time limit is set to 30 minutes in the contract with a power company. However, the CW240 allows you to set the desired demand time limit in units of seconds/minutes

Harmonic Measurement

  • Harmonics for analysis: 1st to 50th
  • Display data: List, bar graph (linear/log), vector (inflow/outflow judgment)
  • Measurement elements: Level, content, phase angle (voltage/current/electric power of each harmonic), aggregate value (voltage,
    current, electric power, power factor), aggregate harmonic distortion factors (THD-F or THD-R) of voltage/current
  • THD-F : Distortion factor for the fundamental wave, THD-R: Distortion factor for all rms values voltage/current
  • Data collection time : 1/2/5/10/15/30/60 minutes

In many cases, inverter power supplies are used to drive air-conditioners and compressors. These power supplies cause distortions in voltages and currents, leading to malfunctions and power loss. Therefore, investigation and control of influences on the main power supplies by harmonics is necessary

Voltage Fluctuation Measurement

  • Measurement element : Voltage dip (voltage drop), voltage swell (voltage rise), instantaneous power failure
  • Data saving : Detected based on the voltage rms value of one waveform. Up to 100 data sets can be saved.

The CW240 detects dates/times of when fluctuations occur, fluctuation type, channels where they occur, rms values, and periods between start and end. The voltage threshold is set, and fluctuations exceeding the threshold are detected

Measures Loads in Four Systems Simultaneously.

The CW240 enables simultaneous measurement of loads in four systems in the case of the single-phase 2-wire system, and in two systems in the case of the single/three-phase 3-wire system (common to voltage). Current clamp probe/range can be set for each system.