- July 19, 2021
- Posted by: Dyaneshwar Nirmale
- Category: Digital Meters
Despite their small size, current transformers handle heavy workload. They have to be in continuous operation over the span of many decades. Proper specification and maintenance of the current transformers in important for reliable protection, and accurate energy metering. The secondary current produced by the CT must be proportional to the current flowing in the power system over the whole range within a defined accuracy. Accuracy is also a critical for metering type CTs. The financial consequences of incorrect measurement and billing could have serious impact on businesses.
Newtek Electricals works to help businesses avoid the downtime that occurs due to damaged current transformers. We provide accurate, durable and reliable current transformers to businesses in shortest lead time. The nylon casing on Newtek transformers protects the devices from fall-related damage as well as high temperature and fire.
Accuracy testing of CTs at Newtek
Our nylon casing CTs are tested with world class Omicron Testing bench which is endorsed by many foreign companies and utilities as mandatory for testing and reliability.
Using the CT analyzer, key parameters of the CT are determined in course of a test run which typically lasts for 1 minute. The CT analyzer, injects a variable frequency signal into the secondary side of the CT and measures the current injected into the secondary terminals and the corresponding voltage applied, as well as the voltage induced on the primary side. The CT analyzer measures the DC winding resistance, the excitation curve, and the turns ratio. It determines all the parameters of the CT model and displays the accuracy data for all current and burden values.
Testing parameters for protection type CTs
The specific testing parameters for protection type CTs include
- Terminal voltage,
- Accuracy limit factor at the actual burden,
- Parameters influencing the CT’s transient behavior
- Rem Alyzer function
A measure is also taken of the CT core’s magnetic remnants, which helps unexpected protection behavior, such as incorrect tripping or non-tripping due to CT saturation. To explore more about how the rated burden and actual burden of a CT is calculated, read our blog on the topic here.
Testing parameters for metering type CTs
- Amplitude and phase angle accuracy for combinations of primary current and burden
- Assessment to check whether the CT is within the specified limits.
- Instrument security factor at the actual burden, verifying the meter’s protection against the overcurrent.
Amplitude and phase error can also be calculated for any combination of primary current and burden required by the user.
Measurement results are then transferred to a PC or laptop for generating reports. The parameters of a measured CT are exported to network simulation programs which then calculate electrical fault currents based on the actual CT behavior.
Other tests for CTs
Newtek nylon encapsulated CTs are certified in line with the UL 94V2 standard which regulates safety norm regarding plastic flammability. It falls within the V2 category which mandates that in case of fire, the burning of material should stop within 30 seconds. Similarly, The cores of our CTs are tested using Waitless Tester to minimize iron losses.
Conclusion
Newtek Electricals has been working for 10+ years to foster continuous improvement and innovation to bring Indian current transformer technology to international standards. Our current transformers have delivered flawless performance for over a decade, emerging as effective substitutes to imports from USA.
If you need standardized, tested and reliable transformers in a short lead time, drop us a mail at sales@newtekelectricals.com or call on +91 – 93728 62651, 93728 62635, and we will respond within 24 hours!