Product Jun. 12, 2014

Hioki Launches Two New High Precision AC/DC Current Probes

Clamp Sensors Offer High-Precision Measurement Over a Broad Temperature Range

Nagano, Japan

Hioki E.E. Corporation is pleased to announce the launch of the AC/DC Current Probe CT6841 (20 A AC/DC rated current) and the AC/DC Current Probe CT6843 (200 A AC/DC rated current) for high precision testing applications particularly in the electric vehicle and hybrid vehicle markets.

The new clamp sensors are engineered to meet demand for the ability to measure current at a high level of precision across a broad range of temperatures in the development of products such as electric vehicles.

Development Background
During development of electric and hybrid vehicles, the need to evaluate motor efficiency requires engineers to measure current flowing in wiring inside the engine compartment at a high level of precision. However, since wiring cannot be removed easily when measuring current in actual vehicles, pass-through current sensors cannot be used. Further complicating the task are high temperatures and a lack of space in the compartment, which houses both the engine and a complex network of wiring. These conditions demand compact, high-precision current sensors that can make measurements in a broad range of temperatures. Hioki’s newly launched CT6841 and CT6843 AC/DC Current Probes meet this measurement need.

Principal Applications
* Evaluation of electric vehicle and hybrid vehicle motor efficiency
(Measuring current inside an engine compartment)
* Evaluation of the efficiency of inverters and power conditioners used in solar power systems

Product Features
1. Ability to make high-precision measurements across a broader range of temperatures than legacy models
Compared to Models 9277 and 9278, both the CT6841 and CT6843 can measure current across a broad frequency band at a high degree of precision. Furthermore, they both feature an operating temperature range of -40C to 85C, allowing their use in a broader range of temperatures than legacy models with a 0C to 40C range. This capability allows the instruments to be used to measure current inside hot engine compartments. Additionally, the new sensors are less susceptible to the effects of noise from nearby wiring than legacy models, allowing more accurate measurement.

Measurement accuracy
 New Models CT6841, CT6843: 0.3%rdg.
 Legacy Models 9277 9278: 0.5%rdg.

Measurement frequency band
 ・New Models
   CT6841: DC to 1MHz
   CT6843: DC to 500kHz
 ・Legacy Models
   9277, 9278: 100kHz

Operating temperature range
 New Models CT6841, CT6843: -40℃ to 85℃
 Legacy Models 9277 9278: 0℃ to 40℃ 
Rated Current
 ・New Models
   CT6841: 20A AC/DC
   CT6843: 200A AC/DC
 ・Legacy Models
   9277: 20A AC/DC
   9278: 200A AC/DC

Additionally, the CT6841 and CT6843 are less susceptible to the effects of noise from nearby wiring than previous models, allowing more accurate measurement.

2. More compact sensor head and grip design to facilitate easier clamp measurement in confined spaces
The confined spaces of automobile engine compartments are filled with engine components and complex wiring networks. The CT6841 and CT6843 feature more compact sensor heads and grips, making it easy to measure current in such limited spaces. Also, whereas legacy models incorporated a sensor head with squared-off edges, the CT6841 and CT6843 have rounded edges so that the sensor head can be more easily applied to wiring in confined spaces.


Established in 1935, HIOKI E.E. CORPORATION (TSE: 6866) has grown to become a world leader in providing consistent delivery of test and measuring instruments through advanced design, manufacturing, and sales and services. By offering over 200 main products characterized by safety and quality while meeting an expansive range of applications, we aim to contribute to the efficiency and value of our customers' work in research and development, production and electrical maintenance. HIOKI products and services are available around the world through our extensive network of subsidiaries and distributors. Information about HIOKI is available at

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CT6841 AC/DC Current Probe

Current testing directly in the engine compartment