YOKOGAWA CTW10 User Manual Download Page 1

Models CTW10, CTW20, CTW100, 

and CTW130

Clamp-on Current  

Transformers

4.  INSTALLATION

 WARNING

Since there is a risk of electric shock during 

installation, be sure to observe the following.

 

Before connecting the transformer to any other 

equipment, make sure the circuit is not receiving 

any power in order to prevent electric shock.

 

Fasten the connecting terminals securely so they 

will not loosen readily.

 

Do not touch the terminals or any other part of the 

transformer when the circuit is live.

 

Do not use the transformer under a circuit current 

greater than the level specified for that model.

 

Do not use the transformer under a circuit voltage 

greater than 500 V AC.

 CAUTION

The CTW contains a device for suppressing hazardous 

voltages that ay arise when the secondary line is open-

circuited.

Install the transformer referring to the following figures.

Cable

Power-source side

K

Load side

L

Secondary-stage cable

k side = white; l side = black

Buckle

Example of Installation

Pull the buckle

in the direction

of the arrow.

How to Remove

Hook

Hook the buckle.

Push the

buckle in the

direction of

the arrow

until it clicks.

How to Install

 

1.  CAUTIONARY NOTES FOR SAFE USE OF THE 

PRODUCTS

The following symbol is used on the product and in this manual to 

ensure safe usage.

 WARNING

Calls attention to actions or conditions that could 

cause serious or fatal injury to the user, and indicates 

precautions that should be taken to prevent such 

occurrences.

 CAUTION

Calls attention to actions or conditions that could 

cause injury to the user or damage to the instrument 

or property and indicates precautions that should be 

taken to prevent such occurrences.

2.  CROSS-CHECK THE MODEL

Make sure the model and suffix codes shown on the data plate 

attached to the transformer are the same as specified in your 

purchase order.

Models

Names

CTW10

Clamp-on Current Transformer (for 100 A / 1 A)

Applicable cable diameter: less than Φ24 mm

CTW20

Clamp-on Current Transformer (for 200 A / 1 A)

Applicable cable diameter: less than Φ24 mm

CTW100

Clamp-on Current Transformer (for 500 A / 5 A)

Applicable cable diameter: less than Φ36 mm

CTW130

Clamp-on Current Transformer (for 800 A / 5 A)

Applicable cable diameter: less than Φ36 mm

3.  HANDLING PRECAUTIONS AND 

INSTALLATION LOCATION

 CAUTION

 

Note that these current transformers are designed 

for use with general-purpose instruments and have 

not yet gained any official certification. They cannot 

therefore be used for the purpose of ascertaining 

wattage or other electric parameters.

 

Use each current transformers under a load no 

greater than its rated level. When calculating 

the load, you must calculate the sum of the load 

given by the instruments to be connected to the 

transformer and the load given by the lead-wire of 

the secondary-stage cable.

 

The inner-walls of the clamp are treated with rust 

preventive. But if rusted, remove the rust with 

CRC-5-56 (goods on the market) and spray rust 

preventive on the inner-walls again for recovery.

Avoid installing the current transformers in locations subject to:

ambient temperatures outside the specified range of -20 °C to 

50 °C, where condensation is likely; ambient humidity exceeding 

80 % RH, where condensation is likely; relatively large amounts 

of flammable or explosive gas, saline substance, lampblack or 

dust; splashes of water, oil or solvent; radioactive rays or intense 

electric or magnetic fields; frequent mechanical vibration or 

shock; or direct sunlight.

IM 77C01W02-01E

©Copyright Nov. 2003

3rd Edition: Nov. 2019

User’s

Manual

1

Thank you for purchasing the Clamp-on Current Transformers.

Please read through this manual before use for correct handling.

2-9-32, Naka-cho Musashino-shi, Tokyo 180-8750 Japan

http://www.yokogawa.com/ns/powercert/

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