Current transformers (CTs) play a crucial role in electrical switchgear systems by accurately measuring electrical currents. While standard CTs are readily available, there are significant advantages to opting for custom-designed CTs tailored specifically for electrical switchgear manufacturers. Here are five key benefits of custom-designed CTs:

1. Enhanced Accuracy: Custom-designed CTs can be manufactured to match the specific characteristics and requirements of the switchgear system or existing installed CTs. By taking into account factors such as the primary current range, burden impedance (VA), and accuracy class, we can achieve superior accuracy in current measurement. This ensures robust and reliable performance, enabling accurate power monitoring and protection of electrical equipment.
2. Optimal Size and Form Factor: Electrical switchgear systems often have unique space constraints due to design considerations or the facility's layout. Custom-designed CTs allow Instrument Transformers Limited (ITL) to manufacture transformers that fit perfectly within the available space, maximising the efficiency and compactness of the switchgear design. This customisation ensures seamless integration and minimises the need for additional modifications or adjustments.
3. Tailored Ratings and Specifications: Standard CTs may not always meet the specific rating requirements of electrical switchgear manufacturers. Custom-designed CTs enable manufacturers like ITL to choose the appropriate ratings, such as current ratios, accuracy classes, and thermal limits, to match the unique characteristics of their customers' switchgear systems. This customisation ensures optimal performance and avoids over or under-sizing of current transformers.
4. Improved Safety and Reliability: Custom-designed CTs can be engineered with advanced safety features and protective measures, enhancing the overall reliability of the switchgear system. Manufacturers can incorporate additional insulation, thermal monitoring devices, short-circuit protection, and other safety mechanisms to mitigate risks and prevent potential failures. This customised approach enhances the safety of personnel and equipment, reducing the likelihood of electrical accidents or downtime.
5. Cost-Effective Solution: While custom-designed CTs may involve an initial investment in design and engineering, they can ultimately provide a cost-effective solution for electrical switchgear manufacturers. By tailoring the CTs to match the specific requirements and constraints of the switchgear system, manufacturers can eliminate the need for costly modifications, minimise downtime, and optimise energy consumption. Additionally, custom CTs' enhanced accuracy and reliability contribute to efficient maintenance, reducing long-term operating costs.

In conclusion, custom-designed current transformers offer several advantages to electrical switchgear manufacturers. From enhanced accuracy and tailored specifications to improved safety and cost-effectiveness, these customised solutions empower ITL customers to optimise their switchgear systems' performance, reliability, and efficiency. Electrical switchgear manufacturers can achieve superior results by partnering with an experienced transformer manufacturer such as Instrument Transformers Limited (ITL) and leveraging our expertise in customisation.

#itl #quality #custom #design #CT #current #transformers #valueformoney

Best Value for Money (Vfm) is the most advantageous combination of cost and quality to meet a customer's requirements.

In this context:

cost means consideration of the whole life cost

quality means meeting a specification which is fit for purpose and sufficient to meet the customer's requirements

Demonstrating our continued strength in providing the best value for money products, we are supplying a new current transformer for one initially delivered by us in November 1978. #itl #quality #VfM #CT #current #transformers #valueformoney

Bit of a wordy headline but as part of my getting the best value out of your purchase series, in this weeks post I am focussing on Metering or Measurement Current Transformers.

When a customer asks for a quotation, he/she may have a price in mind. That might be based on previous purchases or a hunch, but none the less a price is ingrained.

Current Transformers (CT's) while a relatively simple product in nature, sometimes customers are not always sure about what they need and give you a specification that is wildly over-specified for the application. As a CT manufacturer, we understand you are not experts. However, loaded with some knowledge on the factors that can influence price, then there is an opportunity to extract the higher value from your purchase.

RATIO: Primary (input) & Secondary (output) Current Ratio (e.g. 200/5A)

VA: Total instrument burden, including the length of any pilot wires along with square mm of the cable (e.g. 4sqmm).

CLASS: Accuracy required for operation (Tariff, Measurement or Indication

DIMENSIONS: Maximum & Minimum ( the space you have available to fit the current transformer, e.g. for a ring-type Inside Diameter ID, Outside Diameter OD, Axial Length AL).

1. By specifying a higher VA or ACCURACY CLASS than necessary will likely result in a more expensive product.
2. Cost generally increases as the Current Transformers inside diameter (ID) increases.
3. 1A Current Transformers are typically more costly than 5A, why I hear you say - 200/1A has 200 turns of copper whereas 200/5A has 40 turns of copper thus an 80% cost saving on copper, not to mention a reduction in the overall dimensions).
4. Potentially unnecessary accessories such as mountings which are chargeable extras. (Most customers have their own preferred and cheaper method of mounting inside the switchgear).

Considering the above plays a big part in getting the right product for the right price.

For this post, we will consider IEC 61869 as the default standard, as this is our usual customer requirement. However, should you need IEEE/ANSI or AS (Australia) we are just as at home with these specifications?

IEC 61869 standard:

There is also Class 3 & Class 5 but rarely used, most people opting for a Class 1 as a better alternative.

High accuracy classes like 0.2s & 0.5s often require a special type of core material which in itself very expensive, so this accuracy class should only be selected when a tariff application is required.

We appreciate our customers are not specialist in transformer design but have found that one of the most common misunderstood factors about specifying a current transformer (CT) is the Burden or VA. For example, if you double the burden from 5 to 10VA, you will increase the electrical steel content and thus have a significant impact on the unit price so you must get this right.

The burden is the load imposed on the secondary of the CT at rated current and is measured in VA (product of volts and amps). The accuracy class applies only to loads at rated VA and below, down to one-quarter VA. The burden on the secondary of a CT includes the effect of pilot leads, connections etc. as well as the instrument burden itself.

In situations where the meter is remote from the current transformer, the resistance of the pilot wires may exceed the meter impedance many times in these cases it is often economical to use 1 amp meters and CTs.

The diagram shows the burden imposed on the CT due to a run of pilot wire, so a pilot loop of 2.5mm2 wire, 60 metres long (30 metres distance) has a load of 12.5 VA on a 5 amp CT but only 0.5VA on a 1 amp CT.

Typical Meter Burdens (depending on the pilot lead length):

Moving iron meter 1-2VA

Moving coil meter 1-2.5VA

Digital instrument 1-5VA

Maximum demand indicator 3-6VA

Want to find out more about the Principles of Measurement Accuracy? Download our FREE application note.

Got a project where you need help with your CT or VT requirement? Reach out to our engineering team and share your requirements. We're here to help.