Voltage Transformer Design Explained

By R.W. Hurst, Editor

A voltage transformer is an electrical device that converts high voltage from a power source into a proportionally lower secondary voltage. It operates on the principle of electromagnetic induction, with the input voltage applied to the primary winding and the output voltage induced in the secondary winding. The ratio of primary to secondary turns determines the voltage transformation ratio.

How Does A Voltage Transformer Work

A Voltage Transformer operates on the principle of electromagnetic induction. It consists of a primary winding connected to the high voltage line and a secondary winding that delivers a reduced secondary voltage proportional to the primary voltage. When an input voltage is applied to the primary winding, a magnetic field is generated in the core, inducing a voltage in the secondary winding. This process enables the safe measurement and monitoring of high voltage levels without directly exposing measurement instruments to dangerous voltages.

Types of Voltage Transformers

There are several types of voltage transformer, each designed for specific applications:

Power Transformers: Used in power systems to step up or step down voltage levels for transmission and distribution.
Instrument Transformers: Include potential transformers and current transformers, used for metering and protection purposes.
Step Down Transformers: Convert high voltage to a lower voltage suitable for use in homes and businesses.
Step Up Transformers: Increase the voltage from a lower level to a higher level for efficient long-distance power transmission.
Watt Step Up Down Voltage Transformer Converters: Versatile devices that can both increase and decrease voltage levels, often used in applications requiring voltage conversion for various power sources.

Key Considerations for Selection

When choosing a voltage transformer, consider:

Voltage Rating: Ensure the voltage rating of the transformer matches the system voltage.
Accuracy Class: Select the appropriate accuracy class based on the application's requirements.
Burden: Choose a transformer that can handle the burden (power consumption) of the connected instruments.
Environmental Conditions: Consider the operating temperature, humidity, and altitude of the installation.
Additional Features: Some voltage transformers offer additional features like built-in surge protection or digital outputs.

Safety Precautions

A voltage transformer is connected to high-voltage lines, posing significant electrical hazards. Always follow these safety precautions:

De-energize: Ensure the circuit is de-energized and grounded before working on a voltage transformer.
Qualified Personnel: Only qualified and trained personnel should handle or install voltage transformers.
Personal Protective Equipment (PPE): Always wear appropriate PPE, including insulating gloves and safety glasses.

Working with a voltage transformer requires adherence to several safety precautions:

Proper Installation: Ensure the VT is installed by a qualified professional following the manufacturer's guidelines and safety standards.
Insulation: Use appropriate insulation materials to prevent electrical faults and ensure safe operation.
Regular Maintenance: Perform routine inspections and maintenance to identify and rectify potential issues.
Personal Protective Equipment (PPE): Always wear appropriate PPE, such as gloves and safety goggles, when handling VTs.
Grounding: Ensure proper grounding of the VT to prevent electrical shocks and enhance safety.

A voltage transformer is vital for converting voltage levels in electrical systems, ensuring safe and accurate measurement and monitoring of high voltage lines. You can effectively utilize voltage transformers in various applications by understanding its purpose, how it works, the different types available, and key selection considerations. Always follow safety precautions to ensure safe and efficient operation. Whether for metering, protection, or voltage conversion, voltage transformers play a critical role in maintaining the reliability and safety of power systems.

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03/12/20

Evluma Launches Line of Post Top Globes to Complement LED OmniMax

March 12, 2020, Renton, WA…Street and area lighting manufacturer Evluma, announces the release of a new globe accessory line, OmniMax Lighting Solutions (OLS) to complement their OmniMax family of LED replacement lamps. OLS is a custom, curated selection of spherical and acorn style globes for decorative streetlights. The OmniMax is a Bluetooth-connected, screw-in replacement lamp for use in decorative post top globe and acorn lights. The release of a globe line to complement the OmniMax is designed to make the HID to LED conversion and maintenance process easier for Evluma customers.

Customers executing a retrofit project can conveniently purchase a replacement globe at the same time they purchase the OmniMax. “The wide variety of styles and materials offered means that we can typically provide a customer with a globe that matches an older style,” said Marketing Director, Cathleen Shattuck. “Customers can refresh globes simultaneously with OmniMax installation to save on labor, or if they suddenly discover damage to individual light fixtures, we can quickly provide them with a solution. Our high level of customer service means we are well-adapted to quick turnaround on orders of any size, keeping the process convenient and low cost.”

Using OmniMax, municipalities, utilities and electric departments converting post top fixtures from HID to LED can do so in under 5 minutes a fixture. The OmniMax is available in both Premium and Standard models. Premium models are Bluetooth-enabled and are compatible with Evluma’s wireless control application, ConnectLED. Both models carry a ten-year warranty and offer Evluma’s signature low-glare illumination.

About Evluma

Formed in 2008, Evluma is committed to developing affordable, long-lasting and environmentally low-impact LED lighting solutions that fundamentally change the landscape of the outdoor utility lighting market. Evluma’s high standard of customer service and background in innovative lighting technologies, automation and software design creatively ideate and inform its utility-grade products. Evluma is located in Renton, WA, USA.

09/24/20

Evluma's Build-Your-Own Acorn is an Affordable Answer to Decorative Streetlight LED Upgrades

Street and area light manufacturer Evluma announces the release of Build-Your-Own Acorn; a full-fixture, decorative streetlight replacement solution that includes the customer’s choice of acorn globe, finial and capital fitter. This solution is designed for utilities, municipalities, facilities and property managers looking to upgrade their existing decorative lighting from HID to LED and features the OmniMax™ LED lamp as its light source.

“Build-Your-Own-Acorn is a tailored solution that puts control in the hands of the customer,” said Evluma Product Manager Jason Dobbs. “With the value-driven OmniMax at the center of quality, cost-effective options, this is an affordable approach to complete head replacements. Build-Your-Own-Acorn offers the freedom to replace and repair fixtures without being locked into a proprietary OEM solution that may be hard to change later and typically costs more. It’s everything but the pole.”

Build-Your-Own Acorn includes multiple styles of acrylic and polycarbonate globes, in addition to a cast aluminum capital fitter. The capital fits 3 inch and 4 inch poles and is offered in black or green. The 70W OmniMax LED lamp is offered in six different color temperatures ranging from 2000K-5000K in either the Premium or Standard. OmniMax Premium includes Evluma’s patented, maintenance-saving Photocontrol Failsafe™ and compatibility with Evluma’s Bluetooth lighting app ConnectLED™. OmniMax Standard ships without connectivity features or Photocontrol Failsafe built-in.

“Photocontrol Failsafe means never having to replace a failed photocontrol ever again,” said Janine Soper, Evluma’s Regional Sales Manager. “With ConnectLED, the OmniMax Premium can be quickly dimmed or programmed with a dimming schedule, offering additional aesthetic and energy saving opportunities,” said Janine.

Both OmniMax models are supported by robust 20kV/10kA surge protection and the OmniMax’s four layers of thermal management for extended operation in enclosed environments. The capital has a 5 year warranty on the finish. Acrylic globes are warrantied for 5 years against yellowing. The OmniMax and all electronics, including the capital’s optional photocontrol are warrantied for 10 years.

About Evluma

02/22/21

Parallel Resonant AC Test Sets

High Voltage, Inc. is an American test equipment manufacturing company located in rural Copake, NY. We are known for high quality, easy to use equipment and for our commitment to providing the best customer and product support in the industry.

As we matured we expanded into larger products. Cable fault locators (thumpers) as well as higher power ac (HPA) dielectric testers as might be used in a factory environment. Our HPA line of ac testers are available with outputs up to 300 kV ac and power levels up to 40 kVA and can be customized with various levels of control sophistication.

Our new PAR line of ac dielectric testers are designed to meet the needs of those who need power levels up to 250 kVA, to be able to test their highly capacitive test loads. Using ac resonant technology outputs of 50 kV at 5A (for example) are possible with an input of only 230 v, 90 A. That is an input of 20 kVA for an output of 250 kVA. (Model PAR-50250FC5)

The PAR models consist of a control section and a high voltage section. While large, they are transportable by van or trailer for field work. The control section includes the input breaker, variable (motorized) input control, a PLC controller, and connections for controlling the hv section. The high voltage section is a steel tank with a phenolic output bushing. Inside this tank is a variable-core reactor in an insulating oil bath with an air space at the top to allow for thermal expansion.

The variable reactor looks similar to a transformer but has a moveable core that allows the inductance value to vary to match the capacitance of the load, thereby achieving resonance. This effectively cancels the load capacitance, as far as input power requirements are concerned. Once in resonance, the input voltage is increased until the desired output voltage level is achieved. For a capacitive load that must be tested at power frequency the PAR reduces power requirements, as well as test equipment size by one tenth to one thirtieth, compared to a test transformer.

The HVI PAR family of resonant as dielectric testers are perfect for power frequency testing of power cables, rotating machinery, bushings, instrument transformers, transformers, shunt reactors, and many other products.

For more info please contact sales@hvinc.com to discuss your application.
For more information on these and other high voltage test products, contact High Voltage, Inc. at www.hvinc.com, sales@hvinc.com, or call 518-329-3275.

03/07/22

Evluma Launches Low-Glare LED Roadway Luminaire

LED lighting manufacturer Evluma announces the launch of a new roadway lighting product RoadMaxTM. The RoadMax series will include three sizes: small, medium and large and a range of wattages designed to replace legacy HID 100w, 250w and 400w cobraheads. The first model in the series, the RoadMax RX1, with wattages ranging from 30W-70W and an estimated output range of 3,000 to 9,000 lumens, is estimated to start shipping at the end of April 2022.

This sleek and stylish luminaire was designed with RP-8-18 roadway requirements in mind. The unique optical design offers a combination of roadway performance and glare control unprecedented in the industry. “RoadMax is an advancement of Evluma’s reputation for low-glare, visually-pleasing outdoor lighting,” says Taisha Bezzo, National Sales Director. “RoadMax addresses contemporary concerns regarding disability glare and light trespass from roadway lighting while maintaining exceptional pole spacing.”

Multiple luminaire configurations for Type II, Type III and Type V, all with zero-uplight (U0), are offered. Additional features such as a field adjustable wattage selector (FAO), light trespass shields and a choice of photocontrol sockets are available. RoadMax can be customized to include Evluma’s Photocontrol FailsafeTM, a patented technology that solves photocontrol failures on street and area lights. Compatibility with ConnectLEDTM, Evluma’s Bluetooth app for wireless lighting controls, enables dimming and dimming schedules without the need for a network. Evluma’s comprehensive 10-year warranty and signature 20kV/10kA surge protection comes standard with every model.