Rectifiers: Nearly Everything You Need to Know

25 Oct.,2022


Huawei R4850G6 Rectifier Module

What is a Rectifier?

A rectifier is an electrical device used to convert alternating current (AC) into direct current (DC) by allowing a current to flow through the device in one direction only. Diodes work like one-way valves within the rectifier to maintain this flow of current. This process is generally known as “rectification.”

While rectifiers have many uses, they are most often used as the primary components of DC power supplies and high-voltage direct current transmission systems. In an industrial setting, rectifiers are typically spec’d based on voltage applied, current needed in the process, quality of the power, and how the control will be arranged.

Ripple is an important measurement for determining the efficiency and quality of a rectifier. Ripple is the clarity of the power (how clean it is) expressed in a percentage. AC divided by DC equals the percent of ripple.

Since our founding in 1963, Dynapower has been at the forefront of the development of custom and standard rectifier solutions for metal finishing, mining, steel, chemical, defense, and hydrogen production industries worldwide.

Types of Rectifiers

There are a wide variety of industrial rectifiers, including SCR, powerstat, tapswitch, switch mode, IGBT chopper, and thyristor rectifiers. Tapswitch and powerstat rectifiers offer little to no control for operators. They have a very low ripple reading, low amperage, and low cost, yet they are typically very expensive to repair.

Alternatively, SCR, SMPS, and IGBT chopper rectifiers offer seemingly infinite control for operators; they can easily control voltage from top to bottom between zero and 100 percent.

SCR Rectifiers

An SCR rectifier is a semiconductor power supply that meters electricity by opening electrical “valves” that work together to rectify electricity. The longer the “valve” is open, the higher the voltage leaving the rectifier will be.

Dynapower RapidX Series SCR Rectifier

SCR rectifiers are variable voltage DC power supplies that are low frequency, high ripple systems. These systems are rugged and have a history of durability in the market— a number of our customers have systems still running after 40 or 50 years. They regulate and react steadily, carry a lot of power in large copper windings, and are fairly easy to troubleshoot with large, easy-to-identify components.

Switch Mode Power Supplies

A switch mode power supply (SMPS) is an electronic power supply that uses a switch from AC to DC, back to AC, then once again back to DC. This is all done at high frequency allowing for the internal parts to be smaller. They utilize a high primary voltage—where 480VAC input units typically see 700VDC—switching voltages inside the transformer.

With smaller parts, tighter windings, smaller footprints, and an even tinier tolerance, these precision pieces of equipment offer good space efficiency per watt, modern computer interfaces, and intuitive controls.

Switch mode power supplies have been around for roughly 40 years. Traditionally, these were used in smaller current applications and only in the last 10 years or so have large-scale switch modes been successfully deployed.

Dynapower Water-Cooled Switch Mode Power Supply

High Power IGBT Chopper and Thyristor Rectifiers

Dynapower also designs and manufactures high power IGBT chopper and thyristor rectifiers for large applications like green hydrogen production, electrowinning, chlor-alkali production, electro-refining, and other specialized applications.

Our design capabilities include the complete High Power Transformer Rectifier System–inclusive of fully integrated operator interfaces and control systems for a single unit or entire multi-unit SCADA network.

Our IGBT chopper and thyristor rectifiers may also be provided with auxiliary equipment as required by the specification—including switchgear, power factor correction, harmonic filters, heat exchangers and free-standing cooling systems. The chopper rectifier designs consist of high-frequency switching technology in a modular design package that converts the transformer secondary AC voltage to a regulated output DC voltage. Larger power systems are constructed of multiple chopper modules to obtain the specified current requirements.

Dynapower IGBT Chopper Rectifier Dynapower Thyristor Rectifier

Rectifier Cooling Options

Rectifiers can be air cooled, water cooled, oil cooled or hybrid cooled. Traditionally, most rectifier manufacturers offer air or water cooled rectifiers. Air cooled units are typically larger per watt of power because they need more surface area to dissipate the heat, while water cooled units are typically smaller because surface area is not a factor in cooling these units.

Rectifier Maintenance

Although extremely durable and long-lasting, rectifiers do occasionally need repairs. The majority of rectifier issues are caused by the overheating of electrical components, like a circuit board. The root cause of overheating could be corrosion, bad cooling lines, a wrong component put in during a repair, breakdown of organic varnish in the transformer, or poor bussing connections.

Good heat management is important for long-term rectifier maintenance. The general rule of thumb to minimize heat is: clean, flat, and tight:

  1. Keep all contacts clean.
  2. Ensure all electrical surfaces are mounted flat to one another.
  3. All electrical surfaces must be tight.

Why choose a Dynapower rectifier?

Dynapower is your one-stop shop for everything rectifiers, from our expansive lines of pre-engineered and custom rectifiers to our comprehensive aftermarket services— including field service, training programs, spare parts, and controls upgrades.

When considering the purchase of a new rectifier, taking the time to pick the right equipment and maintenance plan can help maximize your uptime while saving your business money while improving safety and performance. Dynapower offers a full range of service and support to keep you powered up and confident in the life of your product.

Rectifier Engineering Upgrades

Dynapower works with our customers to identify areas of their processes that can be improved through engineering upgrades. These include items like safety improvements to ensure that the unit is in compliance and that maintenance work can be performed properly on it.

When implementing our engineering upgrades, we harness our 50+ years in the power supply business to bring our customers the best possible upgrades for your systems. These include improvements like extra thermal sensors, water pressure check valves, fan sensors, flow sensors, chemical contamination sensors, and more.

Rectifier Controls Upgrades

Dynapower offers Touchpad, Touchscreen, and Multi-Unit Controllers for our rectifier units. Our Touchpad Controller can be easily integrated into both SCR rectifiers and switch mode power supplies. These controllers give our customers the ability to make precise voltage adjustments, pulse duration, cycle time, and dwell time.

Rectifier Spare Parts, Preventative Maintenance Plans & Field Service

Dynapower stocks a wide variety of rectifier spare parts for rectifiers, like control boards, thermal switches, all types of fuses, and various rectifier diodes. If you don’t see the part you’re looking for, we have a Spare Parts Hotline at (802) 860-7200 to help you locate it.

Dynapower also offers field service and preventative maintenance services for Dynapower and Rapid Power Technologies equipment and most other rectifier brands. Our field service includes commissioning, repairs, routine maintenance, and equipment evaluation.

Dynapower’s preventive maintenance programs are designed to ensure that your equipment is inspected and adjusted on a regular basis, extending the reliable operating life of the equipment. Our goal is to prevent unnecessary equipment failures, ensure proper operation, and minimize your repair and operating costs.

Rectifier Refurbishment

It’s important to stay on top of your rectifier’s performance and maintenance to prevent issues such as loss of efficiency, system failure, injury, or extended down time. Our rectifier refurbishment program includes a full cleaning and reassembly of your Dynapower or Rapid Power rectifier. We also offer the convenience of a complete in-house refurbishment using our state-of-the-art, industry-leading test equipment.

Whether buying new or looking for service and support for an existing rectifier, contact Dynapower today for all your rectifier needs.