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An outdoor current transformer (CT) is a single-phase, oil-cooled instrument transformer for metering and protection up to 33 kV. Laxmi Engineering, Bhopal, makes outdoor CTs for 11, 22 and 33 kV in Live Tank, Dead Tank and Dead Tank Top-Bottom designs, with accuracy from class 0.1 and primary currents from 5 A to 2500 A and above.
Our CTs are highly reliable and accurate for metering and protection purposes, and all parameters are customised as per the customer's requirements.
Key specifications
| Parameter | Value |
|---|---|
| Construction | Single-phase, oil-cooled, outdoor |
| Voltage ratings | 11 kV, 22 kV, 33 kV |
| Accuracy class | 0.1, 0.2S, 0.5, 1, 3P, 5P |
| Primary current ratings | 5 A to 2500 A and above |
| Short-time current (STC) | Up to 50 kA for 3 seconds |
| Designs | Live Tank, Dead Tank (double bushing), Dead Tank Top-Bottom |
| Secondary terminal box | IP55 |
| Standards | IS 16227 and IEC 61869 |
| Testing | Designs type-tested at NABL accredited labs; in-house 400 kV impulse testing laboratory; all routine tests done in-house |
Types and designs
• Live Tank type - A single bushing design which is high on performance. The top of the current transformer is at high potential and the core-coil assembly is placed in the top tank.
• Dead Tank type - A double bushing design and the most commonly used. It is reliable, easy to handle and has fewer leakage points.
• Dead Tank Top-Bottom design - A single bushing design with a top tank and a bottom tank. Unlike the Live Tank design, the core-coil assembly is placed in the bottom tank, which makes it more stable as the bottom tank is heavier than the top.
Ratings - 33 kV, 22 kV and 11 kV current transformers, with multiple core designs for metering and protection applications.
Applications
• Metering and protection on outdoor systems up to 33 kV.
• Outdoor installations of power utilities.
Frequently asked questions
What is an outdoor oil-cooled current transformer?
It is a single-phase, oil-cooled current transformer built for outdoor use, for metering and protection. Laxmi Engineering makes outdoor CTs up to 33 kV and customises all parameters as per the customer's requirements.
What is the difference between Live Tank, Dead Tank and Dead Tank Top-Bottom CTs?
A Live Tank CT is a single bushing design: the top of the CT is at high potential and the core-coil assembly is in the top tank. A Dead Tank CT is a double bushing design; it is the most commonly used, easy to handle and has fewer leakage points. A Dead Tank Top-Bottom CT is a single bushing design with the core-coil assembly in the bottom tank, which makes it more stable because the bottom tank is heavier than the top.
Which accuracy classes and ratings are available?
Laxmi Engineering outdoor CTs are available for 11 kV, 22 kV and 33 kV in accuracy classes 0.1, 0.2S, 0.5, 1, 3P and 5P, with primary currents from 5 A to 2500 A and above and short-time current ratings up to 50 kA for 3 seconds.
What is the IP rating of the secondary terminal box?
The secondary terminal box on Laxmi Engineering outdoor oil-cooled CTs is IP55.
Which standards and tests apply?
The CTs are made as per IS 16227 and IEC 61869. Designs are type-tested at NABL accredited labs, all routine tests are done in-house, and Laxmi Engineering has an in-house 400 kV impulse testing laboratory at its factory in Govindpura, Bhopal.
Request a quote
Send us your requirement — voltage rating, CT ratio, accuracy class and number of cores — and our sales team will get back to you.
Phone: +91-755-2586141 · Mobile: +91-6261549929 · Email: sales@laxmile.com