What’s best: “TR CU” or “EAC” Certification?

Sometimes we get questions regarding TRCU & EAC and which is best. I thought it would be good to try to help our customers with this short post on what they are and how they are interpreted.

The compliance with current standards of the technical regulation is critical for importing products subject to conformity to Russia and other Eurasian Economic Union member states.

Many manufactures are confused by the conformity assessment process with what's the difference between TR CU Certificate and EAC Certificate?

It is two different names for the same process of conformity assessment, whereby both terms are wrong or incomplete and misleading translation.

The background of the names is historical when the standardisation originated in the former Soviet Union. The new system of standardisation covers a large part of Eurasia.

This system was known as GOST an abbreviation of "Государственный Стандарт", which translates into "state-standard". and was umbrella standardisation in the Soviet economy. 

With the disintegration of the Soviet Union in the 1990s, several of the member states started developing their standard and conformity assessment procedures, to simplify the confusing GOST system.

Around 2002/2003, the "On technical regulation" law passed in the Russian Federation declaring that new technical guidelines are developed. Subsequently, the "Technical Regulation" "TR" formed containing fixed requirements for products, services & manufacturing processes.

Russia, Belarus & Kazakhstan founded their Free-Trade-Association which eventually became known as a "Customs Union" "CU". Allowing a single technical regulation to facilitate the sale of goods & services between the member countries underpinned by a common standard "TR CU"

Later when Kyrgystan & Armenia joined an opportunity to enhance standardisation further, Europes "CE" mark would be an appropriate model in which to combine with, developing into what today is the "EurAsian Confirmaity" or EAC certificate.

Now EAC is the proper standardised name but is commonly interchanged when TR CU, GOST standard is mentioned/required.

Transformers supplied from ITL destined for the EurAsian market will have the correct EAC certification attached. If you need a copy of our certificate for your project, feel free to reach out to us at marketing@itl-uk.com where one of our team will assist.

Getting the best value out of your CT purchase (Pt.1)

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.

Can you use a LV CT in MV & HV Environment?

Can a Low Voltage Current Transformer (CT) be used in a Medium or High Voltage application? Surprisingly, it is a question we get a few times a year and thought it would be beneficial to put this out.

Firstly we must understand the configuration of the switchgear. For example, if the switchgear has a system voltage of 12kV and the CT will be installed on the bare busbars in the medium voltage section. Then yes you will need a CT that's fully rated, and generally, that's where the thought & decision process ends.

But let us dig a little deeper. If the CT is to be installed directly on medium voltage busbars, accordingly it must have an insulation level at least equal to that of the system/cubicle. However, if installing a CT on the medium voltage cable (which is already insulated), in this case, the CT can be a low voltage type (e.g. insulation level 0.72kV) as the cable provides the medium voltage insulation. It is this element that is missed by design engineers and as a result, adds unnecessary cost to the switchgear.

Another scenario is a neutral current transformer, typically on outdoor installations where the CT needs to be installed on an MV or HV system but on the neutral circuit. As such, it will not see the higher MV & HV voltages, so it's possible to use a lower insulation rating for the current transformer. It is critical to note on an MV or HV system were the CT will see "line voltage". Then a fully rated insulated current transformer will be required.

Got more questions about your specific requirement or maybe just a general inquiry, reach out to us at technical@itl-uk.com where one of our highly skilled engineers will assist or check-in on chat at our website https://itl-uk.com or directly with the link https://app.purechat.com/w/ITL-Chat

We look forward to being of service to you soon.

ITL Reaches 30,000!

Latest Current Transformer Solution

ITL 30000/1A current transformer

30000/1A Current Transformer from ITL

When testing current transformers it is always best to inject the appropriate rated primary current to ensure that the product truly can meet service conditions. For lower ratio transformers, there is a trend by customers for traditional transformer testing to be replaced by a CT Analyser which injects voltage and using some fancy algorithms provides test data to show compliance. Whilst helpful on the reporting side and field validation, ITL have elected not to use a CT Analyser for primary testing. Opting to continue traditional testing methods for high ratio current transformers by direct current injection to prove compliance and incorporating hybrid reporting format from a CT analyser.

Led by ITL’s Technical Director Greig McFarlane, the company has invested heavily in upgrading its High Current Test Dept. which allows current transformers to be tested to 30,000 Amps with a secondary ratio of 1 Amp. In keeping with our philosophy of exceed customers expectations of giving exactly what the customer asks for, these secondary ratios can be customised should this be necessary.

With such high ratio transformers, many of ITL’s competitors have chosen to loop multiple cable turns through the primary to achieve high current accuracy resolution and while this may be an acceptable method of testing for other organisations, it is not for ITL. This procedure can have the effect of introducing localised saturation which can influence test results and not reflect true operational performance. Greig said “especially when providing accuracy results at very high levels you want to ensure that any downstream risk is minimised.”

“By using state of the art high accuracy test bridges ensures that we continue surpass our customers’ expectations for accurate, reliable and long service transformers.”

As always, we stand ready to meet our customers’ ever demanding needs for CT /VT measurement & protection solutions, with enthusiasm and look forward to helping you soon.

Call us on +44 1355 236 057, or email sales@itl-uk.com

ITL – TransformingYourWorld.net

Our test reports repository

Making things easier for everyone!

Screenshot 2016-08-25 09.02.33

ITL Test Certificate Example

We are always striving to make our customers’ life as easy as possible. ITL have always been known as the "go to CT/VT guys" but also for a great customer service. Fast responses, knowledge, quick orders, you name it (as in life we have stumbled in our past but more importantly we learn from our mistakes to prevent recurrance). However, our other great asset is efficiency. And that is where Test Reports Repository comes in.

Test Reports, or Test Certificates, are very important part of our products. It may seem they are just a supporting document but they clearly state that our CTs and VTs meet international requirements which is an invaluable information for a buyer and particularly for an engineer.

Traditionally, we supply paper copies or electronic copies of test reports. Sometimes we have buyers, engineers etc. e-mailing/ phoning us asking for duplicate test reports for a particular unit (I'm sure you can relate to this scenario). Emails are not always perfect and get lost, sent to junk or just plain deleted in error and don’t get to the intended recipient for what ever reason. We are sure you know it can get messy. So we created TRR. It is an easy way you can access your current transformer or voltage transformer test report by just logging in and doing quick search. 

It makes life easier for both us and our customer. And that is what ITL is about.

Below you can see a short video of how it works. Or you can have a quick test run here. (Username: C110011; Password: TestCertsTest)

Want to sign up? Take a look here! 

Keep a lookout for our developments.