Overview
The Electrocorder CT-3A-RS is a portable three-phase current logger for load surveys, feeder monitoring, current consumption checks and energy-audit support on lower-current circuits.
Use it when you need to record three-phase current over time on circuits where clamp-on current transformers are practical. The CT-3A-RS records current data using three CT sensors that fit around conductors up to approximately 30 mm diameter, with model-dependent high ranges of 200 A or 400 A.
Best for:
- Three-phase load surveys on smaller conductors.
- Feeder loading checks and current-consumption investigations.
- Energy audits where current trends help identify usage patterns.
- Sites where clamp-on current transformers are convenient and sufficient.
- Temporary monitoring where voltage connection is not required.
Consider another model if:
- You need larger current range or flexible sensors for large conductors, where the EC-3A-RS may be a better fit.
- You need voltage, current, power, energy and power factor together, where the EC-7VAR-RS is more appropriate.
- You need voltage-only monitoring, where an EC-3V or SL-3V voltage recorder may be simpler.
What you get:
- CT-3A-RS logger in the smaller 190 x 120 x 60 mm enclosure.
- Three clamp-on current transformers for conductors up to approximately 30 mm diameter.
- USB download lead, carry case, 12 Vdc power supply, batteries, user instructions and free Electrosoft analysis software.
Set up the logger in Electrosoft, install it at the measurement point, then start recording. When enough data has been captured, connect the logger to a PC by USB and use Electrosoft to view, save, export and report on the results.
Applications
Typical applications: The CT-3A-RS is intended for current-only studies where the circuit can be monitored with clamp-on current transformers. It is a practical choice for routine load checks and smaller three-phase current surveys.
What the CT-3A-RS records:
- Three-phase current using clamp-on current transformers.
- Low range 0.5 A to 60 A.
- High range 4 A to 200 A or 4 A to 400 A, depending on model.
- TRMS average, minimum and maximum values across the selected averaging period.
Why constant sampling matters: many instruments only take periodic snapshots. The Electrocorder continuously samples throughout the averaging period, helping capture short events, changing loads and trend data that can otherwise be missed.
Recording duration depends on the selected averaging period. Short averaging periods can be used for detailed investigations, while longer averaging periods support extended monitoring.
The logger is built into a rugged 190 x 120 x 60 mm enclosure and supplied with clamp-on current transformers, USB lead, carry case and external 12 Vdc power supply. External power is recommended when available to preserve the internal batteries.
Related application guides:
- Load Survey and Current Loggers: for feeder checks, current logging, load surveys and capacity planning.
- Energy Audit Loggers: for energy audits, load profiles, peak demand and before/after savings evidence.
Case Studies
These related Electrocorder case studies, application pages and articles show how this type of logging is used in practical investigations.
Resourceable, Northern Ireland - Energy Audit
A customer energy-audit example where Electrocorder logging was used to support measurement-led energy analysis.
Saving Energy in Industry
An industrial energy-saving application page focused on using recorded data to identify where reductions may be possible.
Energy Auditing
A knowledge page explaining how recorded electrical data supports energy audits, load profiling and evidence-based recommendations.
EV Charging
A blog article where current logging and load monitoring are relevant to understanding electrical demand from charging installations.
Resources
Documentation:
Download the CT-3A-RS datasheet and user instructions for detailed technical information, installation guidance and operating instructions.
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Datasheet |
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User Instructions (English) |
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Datasheet (Español) |
Free Electrosoft PC software
Electrosoft is compatible with Windows 11 down to Windows 7. It lets you view and zoom current, power and energy graphs, export data to Microsoft Excel, email results to colleagues, and print or save reports as PDF files with your company logo.
Electrosoft includes statistics, load balancing, tariff and costing analysis, annual CO2 and energy usage projections, logger management and calibration management tools. Sample files are included so you can try the software without having a logger connected.
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Download Electrosoft PC software |
Features
When to choose the CT-3A-RS
Choose this model when you need a current-only three-phase logger for smaller conductors and routine load surveys.
Compare with related Electrocorder models
If you need larger conductor access or higher current ranges, consider the EC-3A-RS with flexible Rogowski coils. If you need voltage, current, power and power factor together, consider the EC-7VAR-RS.
Key features:
- Three clamp-on current transformers for practical current-only installation.
- Dual ranges for low-current and higher-current monitoring.
- No voltage connection required for logging.
- Configurable averaging period for short investigations or longer-term monitoring.
- Constant sampling to reduce the risk of missing short-duration or changing load events.
- Tamper-resistant setup after configuration in Electrosoft.
Measurement note
The CT-3A-RS records current only. It is useful for current trend analysis and load surveys, but it does not calculate kW, kVA, kVAR or power factor by itself.
Included with your portable three-phase current logger with clamp-on current transformers:
- CT-3A-RS logger in the smaller 190 x 120 x 60 mm enclosure.
- Three clamp-on current transformers for conductors up to approximately 30 mm diameter.
- USB download lead, carry case, 12 Vdc power supply, batteries, user instructions and free Electrosoft analysis software.
Shipping and origin details:
- Harmonised Code: 9030.3901.00 (electronic datalogger).
- Origin: Northern Ireland, United Kingdom.
- Packaged dimensions: approximately 2.5 kg, 30 x 25 x 17 cm.
Determining product order codes:
To specify your Electrocorder select various codes and enter into the boxes in order to create an accurate product code. For example: CT-3A-RS-5H-IP43-SET.
FAQ
When should I choose the CT-3A-RS?
Choose it for current-only three-phase monitoring on conductors where clamp-on CTs are practical.
What is the difference between CT-3A-RS and EC-3A-RS?
The CT-3A-RS uses clamp-on current transformers for smaller conductors. The EC-3A-RS uses flexible Rogowski coils and suits larger conductors or higher current ranges.
Does it need a voltage connection?
No. It is a current logger, so it does not need an AC voltage connection for logging.
Can it calculate power or power factor?
No. For power and power factor analysis, consider the EC-7VAR-RS.
What software is used to analyse the data?
Electrosoft PC software is used to configure the logger, download recorded data, view graphs, export data and create reports.