Best-in-class Measurement Bandwidth with High Accuracy


Hioki's pass-through type AC/DC current sensors can be connected directly to Hioki Power Analyzers and Memory HiCorders. Also, it can be connected to Power Meters, Oscilloscopes, DMMs, etc. by using an optional sensor unit.
The CT6904A has a frequency bandwidth of DC to 4 MHz (Model CT6904A-1 is DC to 2 MHz) and a rated current of 500 A. It is used in research and development fields such as loss measurement of high-frequency reactors, wireless charging systems, and EV inverter motors.

Use with an instrument with a high input impedance of 1 MΩ or higher.

Key Features

  • Combined accuracy with HIOKI power analyzer PW8001 and PW6001 is specified. For details of combined accuracy, refer to the instruction manual.
  • 500 A (rms) rated for measurement of large currents
  • CT6904A: DC to 4 MHz (±3 dB), CT6904A-1: DC to 2 MHz (±3 dB) wide measurement frequency range
  • ±5 ppm excellent linearity
  • 120 dB (100 kHz) high Common-Mode Rejection Ratio (CMRR)

Model No. (Order Code)

CT6904A Cable length: 3 m (9.84 ft.)
CT6904A-1 Build-to-order, cable length: 10 m (32.81 ft.)

Unparalleled technology driving the evolution of current measurement

High-accuracy sensors uses the "zero flux method (flux gate detection type)." High-frequency currents are detected with the winding (CT method), and DC to low frequency currents are detected using a "flux gate."

Flux gate detection

Flux gate detection delivers outstanding linear properties, and can measure currents of a wide range of magnitudes with high accuracy.
The fluxgate components used for DC detection have very low offset over a wide temperature range due to their operating principle, resulting in high accuracy and excellent temperature stability. It is ideal for measurements that require high accuracy, such as Power analyzers and Power meters. It can be used for measurement such as inverter efficiency, inverter output power, reactor/transformer loss, and long-term DC measurements.

Wide frequency band

The CT6904A has a frequency bandwidth of DC to 4 MHz (Model CT6904A-1 is DC to 2 MHz), which is top-class for a 500 A rated pass-through sensor. In combination with the Power Analyzer PW8001, high frequency and low power factor can be measured accurately.

Automatic Phase Correction function

To accurately measure high frequency and low power factor, it is important to correct phase errors. The PW8001 automatically acquires and corrects the phase of the current sensor with 0.001°resolution, bringing out the best performance of the current sensor without any effort.

High Noise Resistance

By completely shielding the oppositely arranged split coils with a unique-shaped solid shield, it achieves both wide bandwidth and superior noise resistance. Accurate measurement can be performed without being affected by ambient voltage.

Automatic detection capability for even greater convenience

Automatic current sensor detection by Power Analyzer PW8001

The current sensor is equipped with a memory (I2C-EEPROM).
When the current sensor is connected to the Power Analyzer PW8001, the phase correction data, rated current, sensor's model name, and serial number are automatically recognized by the instrument.

In the past, phase correction values had to be entered manually.
However, thanks to the automatic detection system of current sensor information, forgetting settings and typing errors are eliminated, allowing for more accurate power calculations.

Basic specifications

Accuracy guaranteed: 1 year
Rated current 500 A AC/DC
Max. allowable input Within the derating range, However, up to ±1000 A peak is allowable if within 20 ms. (design value)
Frequency bandwidth Amplitude: DC to 4 MHz (CT6904A), DC to 2 MHz (CT6904A-1)
Phase: DC to 1 MHz
Linearity ±5 ppm Typical (23°C (73°F))
Offset voltage ±10 ppm Typical (23°C (73°F), no input)
Basic accuracy DC (Amplitude: ±0.025 % rdg. ±0.007 % f.s., No phase specification)
45 Hz ≤ f ≤ 65 Hz (Amplitude: ±0.02 % rdg. ±0.007 % f.s., Phase: ±0.08°)
Output voltage rate 4 mV / A rated (This device outputs AC+DC voltage via the Sensor Unit)
Max. rated voltage to earth 1000 V CAT III
Core diameter φ 32 mm (1.26 in)
Operating temperature, humidity -10°C to 50°C (14°F to 122°F)
80% RH or less (with no condensation)
Power supply Power suppled via the Power Analyzer PW8001, PW6001, PW3390, or Sensor Unit CT9555, CT9556, CT9557
Max. rated power 7 VA Max. (500 A/55 Hz measurement, with a power supply of ±12 V)
Dimensions and mass 139 mm (5.47 in) W × 120 mm (4.72 in) H × 52 mm (2.05 in) D
CT6904A: 1.05 kg (37 oz), cable length 3 m (9.84 ft)
CT6904A-1: 1.35 kg (47.6 oz), cable length 10 m (32.81 ft)
Included accessories Instruction Manual ×1, Carrying case ×1, Color labels (for channel identification) ×1, Operating Precautions ×1

External power supply, connection cord (5)

Conversion cable/extension cable (2)

The CT9902 connects up to 2 cables in series (Accuracy addition required)

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