Hioki CT7731, CT7736, CT7742 Instruction Manual

CT7731

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AC/DC AUTO-ZERO

CT7736

CURRENT SENSOR

CT7742

Instruction Manual

Dec. 2015 Revised edition 1
Printed in Japan
CT7731A961-01 15-12H

EN

Introduction

Thank you for purchasing the Hioki CT7731, CT7736, CT7742
AC/DC Auto-Zero Current Sensor. To obtain maximum per-

formance from the device, please read this manual rst, and

keep it handy for future reference.

Be sure to also read the separate booklet “Current Sensor
Operating Precautions” before use.

Troubleshooting

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

Overview

This current sensor has a Hioki PL14 output connector,
enabling it to be automatically recognized when connected to
a compatible instrument for simple setup.
Furthermore, its features include reduced zero-point variability
caused by temperature, making it well suited to applications
characterized by temperature variations, for example
continuous measurement during daytime and nighttime hours.

Parts Names

Example: CT7736

Output connector

Jaw

Check Items Remedy

Is the jaw cracked or
damaged?

Is the cable insulation torn?

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

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.

• Attach the clamp around only one conductor. If you
clamp single-phase (2-wire) or three-phase (3-wire)
conductors together, the device will not be able to make a
measurement.

• When a conductor to be measured is clamped in the center
of the jaw, measurement is performed the most accurately,
with no effect of the conductor position.

• To measure low current levels, multiple windings may be
used to increase relative sensitivity (10 windings multiplies
the measured current by a factor of 10). However, in this
case, the windings should be made radially, with a diameter
of at least 20 cm.

• The reading may show a measurement greater than the

actual value due to magnetic-eld interference. The amount

of interference varies depending on the sensor. For details,

Clamp the conductor

3

Source

Current direction

Gripping the lever to open the jaw, align the current
direction indicator with the direction of the current in the
conductor, and close the jaw with the conductor roughly
centered in the jaw.
If the phase is not an issue during AC measurement,

the direction of current ow in the wire relative to the

current direction indicator may be ignored.

Close the tips of the jaw completely before performing
measurement. If the output cable is caught on the jaw or
the jaw is forced into the measurement location, it may
not close completely. If this occurs, it will not be possible
to obtain an accurate measurement.

Once measurement is complete, remove the

4

device from the conductor and disconnect it
from the instrument.

When disconnecting the device from the instrument,
grip the tip of the output connector (the part with the
arrow) and pull the connector straight out.

Pulling forcibly on the base of the connector may
damage the device.

see “Magnetic-eld interference” in Specications.

• For more information about instrument operation and

Specications

General Specications

CT7731 CT7736 CT7742

Operating
environment

Operating
temperature
and humidity

Storage
temperature
and humidity

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

−25°C to 65°C (−13.0°F to 149.0°F), 80% RH or less

(no condensation)

−25°C to 65°C (−13.0°F to 149.0°F), 80% RH or less

(no condensation)

Protective barrier

Lever

settings, see the instrument’s instruction manual.

Connect the device to the instrument.

1

Instrument

Align and insert the connector.

Align the arrow on the device’s output connector with

13-09

Cable

Measurement Methods

Inspection Before Use

Verify that the device operates normally to ensure that no

damage occurred during storage or shipping. If you nd any

damage, contact your authorized Hioki distributor or reseller.

the on the compatible instrument’s sensor input
connector and insert the connector.

Perform zero-adjustment. (DC measurement)

2

Perform zero-adjustment under no-input conditions.

Once zero-adjustment has been performed, move­ment of the device’s zero-point will be within the
guaranteed range. Consequently, you must per­form initial zero-adjustment before use.

Dustproof and
waterproof

(EN60529)

Standards

Dielectric
strength

Power
consumption
category

Dimensions

Jaw, barrier, grip:
IP40

Safety: EN61010
EMC: EN61326

7.4 kV AC for 1 minute (between jaw and grip, between
jaw and output connector)

Sensor power consumption category: 2
(See the continuous operating time for the instrument to
which the device is to be connected.)

(Not including dimensions of protruding parts, lever, or
jaw)

Approx. 58W ×
132H × 18D mm
(2.28″W × 5.20″H
× 0.71″D)

1 2 3 4

Load

Conductor

Current direction indicator

Jaw, barrier: IP50
Grip: IP54 (when measuring an
insulated conductor only)

Risk of electric shock from the

conductor being measured increases
when wet.

Approx. 64W ×
160H × 34D mm
(2.52″W × 6.30″H
× 1.34″D)

Approx. 64W ×
195H × 34D mm
(2.52″W × 7.68″H
× 1.34″D)

CT7731 CT7736 CT7742

2.0

2.0

2.0

Jaw
dimensions

Mass
Cable length Approx. 2.5 m (98.43″)

Product
warranty period

Accessories

Approx. 66W ×
13D mm (2.60″W
× 0.51″D)

Approx. 250
(

8.8

oz.)

3 years
Instruction Manual,

Current Sensor Operating Precautions

Approx. 69W ×
14D mm (2.72″W
× 0.55″D)

g

Approx. 320
(

11.3

oz.)

Approx. 92W ×
18D mm (3.62″W
× 0.71″D)

g

Approx. 510
(

18.0

oz.)

Output Specications and Measurement

Specications

(1) Basic specications

CT7731 CT7736 CT7742

Output
connector

Rated
measurement
current

Output rate 1 mV/ A 1 mV/ A 0.1 mV/ A

Maximum
measurement
current

Frequency
band

Measurable
conductor
diameter

Sampling
frequency

Maximum rated
voltage to earth

CT7731 Frequency derating

Measurement current [A]

Hioki PL14

100 A AC/DC 600 A AC/DC 2000 A AC/DC

RMS value, continuous:

see “Frequency deratings” below.
Peak value

(under the RMS value conditions described above.):

150 A peak 900 A peak 2840 A peak
DC to 5 kHz (−3 dB)

33 mm (

φ

or less

36.5 kHz ±0.2 kHz

600 V AC/DC
(Measurement
category I

Anticipated transient overvoltage: 8000 V

1.30″)

φ

V)

33 mm (

φ

or less

1000 V AC/DC
(Measurement category III)
600 V AC/DC
(Measurement category IV)

1.30″)

φ

55 mm (

φ

or less

g

2.17″)

φ

CT7742 Frequency derating

Measurement current [A]

Frequency [Hz]

(2) Accuracy specications

f.s.: The rated measurement current.
rdg.: The value currently being measured and indicated on the measuring

instrument.

CT7731 CT7736 CT7742

Guaranteed accuracy period: 3 years
Guaranteed accuracy period

after adjustment made by Hioki:

Conditions of
guaranteed
accuracy

Measurement
accuracy

Temperature

coefcient

Offset drift

(Between −25°C
and 65°C,

Reference

value: at 23°C)

Effect of radiated radio-frequency electromagnetic eld

Effect of conducted radio-frequency electromagnetic eld

Effect of conductor position (deviation from center)

Effect of external magnetic eld (400 A/m, DC)

Maximum cord
extension
length

Opening and closing of the jaw: 30000 times or less
Accuracy guarantee for

temperature and humidity:
After performing zero-adjustment with the instrument to

which the device is connected
Accuracy of AC measurement guaranteed for sine wave

inputs
See separate table.

In the operating temperature range, add 0.1 × specied
accuracy/°C (at temperatures other than 23°C±5°C).

Within

Within ±0.5% f.s.

15% f.s. at 10 V/m

10% f.s.

at 3 V

Within ±1.5% Within ±2.0% Within ±1.0%

Within ±1.5% f.s. Within ±0.5% f.s. Within ±0.2% f.s.

100 m (Depends on the instrument to which the device is
to be connected.)

±0.1% f.s.

3 years

23°C±5°C (73°F±9°F),
80% RH or less

Within

±0.1% f.s.

CT7731 Measurement accuracy

≤

Frequency DC

≤

I
Amplitude
(A)

Peak
(A peak)

Phase – ±1.8 deg.

80

≤

80 < I

100

≤

|I peak|

110 < |I peak|

150

110

≤

±1.0% rdg.
±0.5% f.s.

±1.0% rdg.
±2% f.s.

45

(Hz)

±1.0% rdg.
±0.5% f.s.

±1.0% rdg.
±2% f.s.

CT7736 Measurement accuracy

≤

Frequency DC

≤

±2.0% rdg.
±0.5% f.s.

±2.0% rdg.
±0.7% f.s.

±4.0% rdg.
±0.7% f.s.

Amplitude (A)

≤

Peak
(A peak)

Phase – ±1.8 deg.

|I peak|

600 < |I peak|

900

600

45

(Hz)

±2.0% rdg.
±0.5% f.s.

±2.0% rdg.
±0.7% f.s.

±4.0% rdg.
±0.7% f.s.

CT7742 Measurement accuracy

≤

Frequency DC

≤

I
Amplitude
(A)

Peak
(A peak)

Phase – ±2.3 deg.

1800

1800 < I

|I peak|

2300 < |I peak|

2840

≤

≤

2000

2300

±1.5% rdg.
±0.5% f.s.

±1.5% rdg.
±1.0% f.s.

≤

±6.0% rdg.
±1.5% f.s.

45

(Hz)

±1.5% rdg.
±0.5% f.s.

±2.0% rdg.
±0.5% f.s.

±1.5% rdg.
±1.0% f.s.

±6.0% rdg.
±1.5% f.s.

f ≤ 66

f ≤ 66

f ≤ 66

DC < f <
66 < f ≤ 500

(Hz)

±2.0% rdg.
±0.5% f.s.

±2.5% rdg.
±0.5% f.s.

±2.0% rdg.
±2% f.s.

±2.5% rdg.
±2% f.s.

DC < f < 45
(Hz):

±1.8 deg.

≤

66 < f

500

(Hz):

Not dened.

DC < f <

66 < f ≤ 1 k

(Hz)

±3.0% rdg.
±0.5% f.s.

±3.0% rdg.
±0.7% f.s.

±5.0% rdg.
±0.7% f.s.

DC < f < 45
(Hz):

±1.8 deg.

≤

66 < f

1 k

(Hz):

Not dened.

DC < f <

66 < f ≤ 1 k

(Hz)

±2.5% rdg.
±1.0% f.s.

±2.5% rdg.
±1.0% f.s.

±7.0% rdg.
±1.5% f.s.

DC < f < 45
(Hz):

±2.3 deg.

≤

66 < f

1 k

(Hz):

Not dened.

45,

45,

45,

Zero-point Temperature
Characteristics

Hall elements are subject to individual variation. Reference

examples are provided below to illustrate zero-point variation

(23°C reference) relative to temperature variations for each

sensor. (There is also a variation in characteristics among
individual products.) The operating temperature range is

−25°C to 65°C (−13°F to 149°F).

(See below for example characteristics.)

CT7731

1.0

0.0

電流(A)

Current [A]

-1.0

-2.0

CT7736

1.0

0.0

電流(A)

Current [A]

-1.0

-2.0

CT7742

1.0

0.0

電流(A)

Current [A]

-1.0

-40 -20 0 20 40 60 80

Temperature [°C]

温度(℃)

-40 -20 0 20 40 60 80

Temperature [°C]

温度(℃)

No.1
No.2
No.3

No.1
No.2
No.3

No.1
No.2
No.3

CT7736 Frequency derating

Measurement current [A]

-2.0

Frequency [Hz]

“Peak input” is only available in conjunction with CM7290

Display Unit. For more information about the combination

-40 -20 0 20 40 60 80

Temperature [°C]

温度(℃)

accuracy with the instrument, see the instrument’s instruction
manual.
Amplitude accuracy design value is DC < f < 5 Hz. Phase
accuracy design value is DC < f < 10 Hz.

Frequency [Hz]

5 6 7 8