Using the robust and proven HV DryShield® insulation technology combined with a Rogowski coil sensor the evolution to a digital operation current transformer (CT) was a straightforward process. The HV DryShield® electronic CT uses a dead tank design that houses the sensor and primary converter in a grounded box which provides shielding from electromagnetic interference, […]
Grading Condenser and Uniform Field Design of the HV DryShield Current Transformer
The HV DryShield® line of CTs has been designed for a very long component and operating life. To achieve this the design looks at achieving optimum performance in three specific areas: A Low Dielectric Loss for the Main Insulation Material The tanδ of the insulation material is very important to the design. Too high a […]
Ratings and Service Conditions of HV Dry Type Current Transformers
The HV DryShield® line of CTs can be designed to meet the specific requirements of customer specifications including full compliance with all types of international standards (IEC, IEEE, CAN/CSA, etc.). The internal and external insulation materials used in the HV DryShield® type LRGBJ current transformer design provides a piece of equipment that is safe and […]
Structure, Insulation and Characteristics of HV Dry Type Current Transformers
The next series of articles in our blog will review the history and development of HV dry type current transformers (CTs); and in particular the line of dry type current transformers that was developed in the 1980’s and later patented in the 1990’s and trademarked as HV DryShield®. For decades utilities have been seeking to […]
Equipment Testing Capabilities of the RHM High Voltage Laboratory in New Hampshire
In this month’s article the testing capabilities of RHM International’s new High Voltage Test Laboratory are discussed in more detail. The main purpose of the lab is to provide routine testing for RHM International’s manufactured products (bushings, current transformers, cable terminations) with nominal voltages up to 500-600kV. The lab also can perform high-voltage insulation tests […]
New RHM International HV Testing Laboratory in New Hampshire
For Routine & QA Testing of MV, HV and EHV Dry Type Bushings, Current Transformers and Cable Terminations RHM International’s marketing plans required expansion of their product manufacturing facilities outside of China. As a first step in this plan a new manufacturing plant to serve the North American and European markets was constructed in the […]
Transformer Bushing Standards
In North America the three main bushing standards that are used are CAN CSA C88.1, IEEE C57.19.00/C57.19.01 and IEC60137. The CSA standard is in large part an adoption of the IEEE standard with some specific Canadian requirements (e.g. operational capability at -50°C is seen more as a standard requirement than a special requirement). However dimensional […]
Transformer Bushing Replacement – RHM International Supplies Like for Like Non-Standard Transformer Bushing Dimensions
Continuing with the topic of bushing replacements and the challenges of replacing vintage style oil-filled bushings with current standard bushings, the following is an example of how the RIF® dry type bushing technology could meet the non-standard dimensional requirements of a COTA bushing replacement. Replacement of a COTA 138 kV, 800 A, 650 kV BIL […]
Do You Have a Transformer Bushing Replacement Program?
Most utilities today are operating with an aging transformer fleet that although significant may still have 10 to 20 years of life expectancy. However with these aging assets comes the problem of component reliability. To ensure that the transformers can meet their projected life expectancies money has to be spent replacing or refurbishing key components […]
