Hioki CT6904A-3 Instruction Manual

CT6904A-2

1000

M

Max current [A]

Frequency [Hz]

www.hioki.com/

HIOKI CT6904G961-00

CT6904A-3

AC/DC CURRENT SENSOR

Instruction Manual

Dec. 2021 Edition 1
CT6904G961-00 21-12H

Warranty

Malfunctions occurring under conditions of normal use in conformity
with the Instruction Manual and Product Precautionary Markings will
be repaired free of charge. This warranty is valid for a period of three
(3) years from the date of purchase. Please contact the distributor
from which you purchased the product for further information on
warranty provisions.

Introduction

Thank you for choosing the Hioki CT6904A-2, CT6904A-3 AC/DC

Current Sensor (800 A rated specication). To ensure your ability to 

get the most out of this device over the long term, please read this
manual carefully and keep it available for future reference.

Carefully read the separate document entitled “Operating
Precautions” before use.

Troubleshooting

If the device seems to be malfunctioning, contact your authorized
Hioki distributor or reseller.

DANGER

If the cable melts, metal parts could be exposed, posing

•

a hazard. Keep the cable away from sources of heat.
Connect the device to the secondary side of a

•

distribution panel. If a short-circuit occurs on the
secondary side of the distribution panel, the panel will
interrupt the short-circuit current. Do not connect the
device to the primary side of the distribution panel
because an unrestricted current ow can damage the
device and facilities if a short-circuit occurs.

Do not use the device to measure bare conductors to
which a voltage that exceeds the maximum rated line-to­ground voltage is being applied. Doing so could damage
the device and cause bodily injury. If the voltage exceeds
the maximum rated line-to-ground voltage, measure
it using an insulated wire with the appropriate level of
insulation for the voltage in question.

EN

WARNING

Do not place the cable in contact with the
measured line. Any contact can cause the device
to malfunction and lead to a short-circuit or electric
shock.

CAUTION

• To prevent cable damage, do not step on cables or pinch
them between other objects. Do not bend or pull on cables
at their base.

• Do not place the device on an unstable or uneven surface.
Doing so could cause the device to fall or turn over, causing
bodily injury or damage to the device.

• The cable is hardened in freezing temperatures. Do not
bend or pull it to avoid tearing its shield or causing a break.

• When the power to lines to be measured is turned on or o󰀨, 

a current owing through the lines can exceed considerably 

the maximum allowable current of the device. This could
result in damage to the device. Make sure that there is not
any over-current.

• Do not apply any current through the lines to be measured

with the device turned o󰀨. This could result in damage to the 

device.

Overview

This current sensor has a Hioki ME15W output connector.
The sensor has the adequate frequency characteristics and
temperature characteristics for not only current measurement but
also high-accuracy power measurement.

Specications

The CT6904A-3 has a 10 m output cable.

Accuracy

Reading (displayed value):

Indicates the value displayed by the instrument. Limit values for reading
errors are expressed as a percentage of the reading (“% of reading” or
“% rdg”).

Range:

Indicates the instrument’s range. Limit values for range errors are
expressed as a percentage of the range (“% of range” or “% rng”).

Full scale (rated current):

Indicates the rated current. Limit values for full-scale errors are expressed
as a percentage of full scale (“% of full scale” or “% f.s.”).

Operating
environment

Operating
temperature and
humidity range

Storage
temperature and
humidity range

Dust resistance
and water
resistance

Standards Safety: EN 61010

Withstand voltage 7.4 kV AC (sensed current: 1 mA) 50 Hz/60 Hz for

Power supply Supplied from PW8001, PW6001, PW3390, CT9555,

Maximum rated
power

Interface Dedicated interface (ME15W)
Dimensions Approx. 139W × 120H × 52D mm

Output cable
length

Mounting hole
diameter

Indoor use, pollution degree 2,
altitude up to 2000 m (6562 ft.)

−10°C to 50°C (14°F to 122°F)

80% RH or less (non-condensing)

−20°C to 60°C (−4°F to 140°F)

80% RH or less (non-condensing)

IP20 (EN 60529)*

EMC: EN 61326

1 min, between through window and cable output
terminal

CT9556 or CT9557
Rated supply voltage: ±11.5 V to ±12.5 V (Tracking)
Maximum rated current: ±450 mA (800 A/55 Hz
measurement, ±12 V power supply)

7 VA (800 A/55 Hz measurement, ±12 V power supply)

(5.47″W × 4.72″H × 2.05″D)

(excluding protrusions and the cable)
CT6904A-2: Approx. 3 m (including relay box)

CT6904A-3: Approx. 10 m (including relay box)

5.2 mm (M5 screw, recommended tightening torque:

φ

1.5 Nm to 2.0 Nm)

1

Weight

Product warranty
duration

Accessories • Colored labels (for channel identication)

Option Mounting hardware (special-order product)
Memory Function Sensor information can be read for products with

*1: The protection rating for the enclosure of this device (based on

EN 60529) is IP20.

2:

Protected against access to hazardous parts with ngers. The equipment 

inside the enclosure is protected against entry by solid foreign objects
larger than 12.5 mm in diameter.

0: The equipment inside the enclosure is not protected against the

harmful e󰀨ects of water.

Rated current

Measurable
conductor
diameter

Maximum input
current

Output voltage

Maximum rated
line-to-ground
voltage

Output resistance 50
Input impedance 2.5 m
Linearity*
O󰀨set voltage*

*2: Measuring the output voltage while cycling the input current (DC) from

*3: Dened as a percentage of the rated current.

Accuracy guarantee
conditions

Measurement accuracy

50 kHz < f ≤ 100 kHz 1% + 0.063% ±(0.08 × f)°

100 kHz < f ≤ 300 kHz 2% + 0.063% ±(0.08 × f)°

• The variable f in accuracy equations is expressed in kHz. Full scale indicates the rated
current (800 A).

• Amplitude accuracy and phase accuracy are dened for currents of the rated value or 

less. For currents at a frequency of 100 Hz or greater, they are dened at an ambient 

temperature of 50°C within the continuous input range as shown in Figure 1, “Frequency
Derating.” However, design values are given for DC < f < 10 Hz.

• For the CT6904A-3, add an amplitude accuracy of ±(0.015 × f)% of reading for

50 kHz < f ≤ 1 MHz. CT6904A-3 has a frequency band of 2 MHz (±3 dB typical).

Output noise 300 µV rms or less (≤1 MHz)
E󰀨ects of

temperature

E󰀨ects of
magnetization

Common mode
rejection ratio
(CMRR)

E󰀨ects of
conductor position

2, *3

+800 A → 0 A → −800 A → 0 A → +800 A at an interval of 200 A.
Dened as the di󰀨erence between the regression line calculated from

the above measurements and the measurement points.

Frequency

DC 0.030% + 0.009% –

DC < f < 16 Hz 0.2% + 0.025% ±0.1°

16 Hz ≤ f < 45 Hz 0.1% + 0.025% ±0.1°

45 Hz ≤ f ≤ 65 Hz
65 Hz < f ≤ 850 Hz
850 Hz < f ≤ 1 kHz 0.1% + 0.013% ±0.4°

1 kHz < f ≤ 5 kHz 0.4% + 0.025% ±0.4°

5 kHz < f ≤ 10 kHz 0.4% + 0.025% ±(0.08 × f)°

10 kHz < f ≤ 50 kHz 1% + 0.025% ±(0.08 × f)°

300 kHz < f ≤ 1 MHz 5% + 0.063% ±(0.08 × f)°

Frequency range 4 MHz (±3 dB Typical) –

CT6904A-2: Approx. 1.15 kg (40.6 oz.)
CT6904A-3: Approx. 1.45 kg (51.1 oz.)

3 years

• Instruction Manual

• Operating Precautions (0990A907)

• Carrying case

memory function support. Applicable product: PW8001

800 A AC/DC

32 mm or less

φ

Not exceeding derating curve shown in Figure 1
However, a current of up to ±1200 A peak (design value)
is allowable for up to 20 ms.

2 mV/A

1000 V (Measurement category III)
Anticipated transient overvoltage: 8000 V

±10

Ω

Ω

typical (100 kHz)

Ω

±12.5 ppm typical (23°C)

3

±10 ppm typical (23°C, no input)

Accuracy guarantee duration: 1 year
Accuracy guarantee duration after adjustment made by
Hioki: 1 year
Accuracy guarantee temperature and humidity range:
23°C ±5°C (73°F ±9°F), 80% RH or less
Warm-up time: at least 30 min
Sine wave inputted, connected with measuring
instrument with an input resistance of 0.9 MΩ to 1.1 MΩ,

line-to-ground voltage: 0 V, no external magnetic eld, 

conductor arranged at center of window

±(% of reading + % of full scale)

Within the range of −10°C to 18°C or 28°C to 50°C

Amplitude sensitivity: ±50 ppm of reading/°C

O󰀨set voltage: ±5 ppm of full scale/°C

Phase: ±0.01°/°C

5 mA or less (input equivalent, after 800 A DC is input)

140 dB or more (50 Hz/60 Hz)
120 dB or more (100 kHz)

(E󰀨ect on output voltage / common-mode voltage)

±0.01% of reading or less (input current: 100 A with
50 Hz/60 Hz)
±0.2% of reading or less (input current: 10 A with
100 kHz)
When using wire with an outer diameter of 10 mm

Amplitude

0.025% + 0.009%

0.05% + 0.009%

Phase

±0.08°
±0.12°

E󰀨ects of radiated radio-frequency electromagnetic eld

0.625% of full scale or less at 10 V/m

E󰀨ects of conducted radio-frequency electromagnetic eld

0.25% of full scale or less at 10 V

E󰀨ects of external
magnetic eld

100 mA or less (input equivalent, under a magnetic eld 

of 400 A/m DC or 400 A/m with 60 Hz)

Connectable products

When connected to an instrument that automatically detects current sensors, the
device will be detected as a 1000 A rated sensor.

1. PW8001 Power Analyzer

-1. U7001 Combined accuracy

U7001 accuracy + sensor accuracy (consider sensor rating for full scale error).

• Additional components should be added to the accuracy depending on the power

analyzer and sensor specications.

• Detected as a 1000 A rated sensor.

-2. U7005 Combined accuracy

Frequency

DC 0.050% + 0.037% 0.050% + 0.037%

45 Hz ≤ f ≤ 65 Hz 0.035% + 0.027% 0.035% + 0.037%

Band other than

DC and

Hz ≤ f ≤ 65 Hz

45

• For other measurement parameters, U7005 accuracy + sensor accuracy (consider
sensor rating for full scale error).

• For the 20 A range or the 40 A range, add ±0.12% of
range set on the U7005.

• Additional components should be added to the accuracy depending on the power

analyzer and sensor specications.

• Detected as a 1000 A rated sensor.

Current Power

±(% of reading + % of range)

U7005 accuracy + sensor accuracy

(consider sensor rating for full scale error.)

full scale of the measurement

Phase

U7005

accuracy

+

sensor

accuracy

2. PW6001 Power Analyzer

Combined accuracy

Frequency

DC 0.050% + 0.037% 0.050% + 0.057%

Hz ≤ f ≤ 65 Hz 0.045% + 0.027% 0.045% + 0.037%

45

Band other than

DC and

Hz ≤ f ≤ 65 Hz

45

• For other measurement parameters, PW6001 accuracy + sensor accuracy
(consider sensor rating for full scale error).

• For the 20 A range or the 40 A range, add ±0.12%
range set on the PW6001.

• Additional components should be added to the accuracy depending on the power

analyzer and sensor specications.

• Detected as a 1000 A rated sensor.

Current Power

±(% of reading + % of full scale)

(full scale = PW6001 range)

PW6001 accuracy + sensor accuracy

(consider sensor rating for full scale error.)

full scale of the measurement

Phase

PW6001
accuracy

+

sensor

accuracy

3. PW3390 Power Analyzer

Combined accuracy

PW3390 accuracy + sensor accuracy

• Additional components should be added to the accuracy depending on the power

analyzer and sensor specications.

• Detected as a 1000 A rated sensor.

(consider sensor rating for full scale error)

4. CT9555, CT9556, or CT9557 Sensor Unit

Combined accuracy

For the CT9555, use the sensor accuracy. For the CT9556/CT9557, add ±0.01%
of reading to the sensor accuracy (when the output coaxial cable is 1.6 m or less in
length).

• For the CT6904A-3, the frequency band is 1 MHz (±3 dB typical).

• Additional components should be added to the accuracy depending on the

connected device and sensor specications.

Figure 1. Frequency Derating

800 A

100

10

750 A

1 min. at an ambient temperature of 50°C
Continuous input at an ambient temperature of 30°C
Continuous input at an ambient temperature of 40°C
Continuous input at an ambient temperature of 50°C

1

DC

10 100 1 k 10 k 100 k 1 M 10

When measuring current close to the derating, allow a cool-down
time of at least 10 times the time for which the current was input.

Phase Compensation Values

0.05

0.05

Phase error (deviation from center) [°]

Gain error (deviation from center) [% of reading]

Position

52

139

120

91.2

91.2

91.2

91.2

14.4

14.4

14.4

14.4

14.4

14.4

14.4

14.4

4×

φ

5.2

110

30

22

NO

HIOKI CT6904G961-00

Part Names and Dimensions

Example Installation/Mount

Measurement Procedure

Enter the following compensation values (characteristic values)
when performing phase compensation on the PW6001 or PW3390.

300kHz, −9.82°  (CT6904A-2, CT6904A-3 common)

The 300 kHz phase measured value noted in the test report can be
used as the phase compensation value. In theory, using this value
will allow more accurate measurement than is possible when using
the representative value. There’s no need to enter compensation
values for the PW8001 as that instrument reads sensor information
from memory and performs compensation automatically.

Characteristics

(CT6904A)

Frequency characteristics (Typical)

2

0

-2

-4

-6

Gain error [dB]

-8

-10

Gain
Phase

(compensated)

Phase

10 100 1 k 10 k 100 k 1 M

Frequency [Hz]

4

2

0

-2

Phase [°]

-4

-6

-8

CMRR (Typical)

200

180

160

140

CMRR [dB]

120

100

Sample 1
Sample 2
Sample 3

10 100 1 k 10 k 100 k 1 M 10 M

Frequency [Hz]

Measurable conductor
diameter: φ32 mm or less

Current direction indicator

Output connector
(With lock function)

Relay box

Cable

Mounting hole dimensions

FrontLeft

Cable

Mounting hole

Through window

(Unit: mm)

Serial number and model (Rear)

The rst four digits of the 9-digit 

number indicate the year (its last
two digits only) and the month of
manufacture. Do not remove this
sticker as the number is important.

To facilitate high-precision measurement, the measured conductor
must be as short as possible. Determine how to mount the device so
that the measured conductor is as short as possible.

Recommended tightening conditions

Nominal screw size: M5
Screw length: 20 mm or more
Tightening torque: 1.5 Nm to 2.0 Nm
Use a washer and lock washer

There are two ways to mount the sensor:

1. Using the mounting hardware

The sensor can be mounted in four orientations.

Orientation 1

Mounting hardware

Orientation 2

Orientation 3

Inspection Before Use

Check the device for any damage that may have occurred during

storage or shipping before use. If you nd any damage to the device, 

please contact your authorized Hioki distributor or reseller for repair.

Check Items Remedy

Is the device cracked or damaged?

Is the cable insulation torn?

Is the cable broken at the base (of
the connector or the sensor)?

If there is any damage, electric
shock may result. Discontinue use
and contact your authorized Hioki
distributor or reseller.

Broken connections will make
proper measurement impossible.
Discontinue use and contact your
authorized Hioki distributor or
reseller.

Wiring

Make sure the direction of the arrow on the case matches the

direction of the current ow, as shown in the gure below. If they 

are oriented incorrectly, the output signal from the sensor will be
reversed. When using the device in combination with a power meter,
conform to the power meter’s wiring method.

High

SOURCE

I

Low

IMPORTANT

LOAD

Arrow on case
(Current direction indicator)

E󰀨ects of conductor position (Typical)

E

F

A

D

B

C

Sample 1 Phase

Sample 2 Phase

Sample 3 Phase

0.04

0.03

0.02

0.01

0.00

-0.01

-0.02

-0.03

-0.04

-0.05

Sample 1 Gain

Sample 2 Gain

Sample 3 Gain

A B C D E F

Linearity error (Typical)

60

40

20

0

-20

Linearity error [ppm]

-40

-60

-800 -600 -400 -200 0 200 400 600 800

Sample 1
Sample 2
Sample 3

Input current [A]

(at 100 kHz)

0.04

0.03

0.02

0.01

0.00

-0.01

-0.02

-0.03

-0.04

-0.05

(Mounting hole
thickness: 7.5)

Mounting hardware dimensions (Option)

4.6

5.2

29.8 29.8

14.4

91.2

M5 press nut (×2)

M5用プレスナット(2箇所)

14.4

2

(Unit: mm)

2

(Unit: mm)

Orientation 4

2. Mounting directly

The sensor can be mounted in the desired orientation.

Pass only one conductor through
the device.

OK

Passing two or more of
conductors in a bundle prevents
the device from measuring any
current regardless of whether
the measurement target is a
single-phase or three-phase
circuit.

Shielded

Ground-shielded conductors
cannot be accurately measured.