What is a Rectifier?
From an Industrial Perspective
What Exactly is a Rectifier?
Essentially, 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. Rectification is the general way to describe this process.
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. When speaking about rectifiers, we are talking from an industrial perspective (as opposed to pure electrical engineering—in which the term “rectifier” refers to anything that converts AC to DC). As such, rectifiers are typically spec’d in an industrial atmosphere based on voltage applied, current needed in the process, quality of the power and how you’re going to arrange controls.
Ripple is an important measurement for determining the efficiency of a rectifier. Ripple is the clarity of the power (how clean it is) expressed in a percentage. AC divided by DC equals the % ripple. This is the clarity component of measuring rectifier quality–and a factor that organizations such as NADCAP, the IATF and others require companies to measure.
Currently, there are roughly 25 manufacturers of DC power supplies in the industrial market. Since our founding in 1963, Dynapower has been at the forefront of the development of custom and standard rectifier solutions for the automotive, aerospace, mining, water and waste treatment, steel, chemical, defense, and finishing industries worldwide.
Types of Rectifiers
SCR, SMPS, Large Thyristor & Chopper Rectifiers
There are a wide variety of industrial rectifiers including: SCR, power stat, tap switch, switchmode. choppers and IGBT rectifiers. Tapswitch and powerstat rectifiers offer little to no control for operators. They boast a very low ripple reading, low amperage, low cost but they are very expensive to repair.
Alternatively, SCR, SMPS and chopper rectifiers offer seemingly “infinite” control for operators. For instance, operators can easily control voltage from top to bottom between zero and 100 percent.
“Rectifiers are either infinitely adjustable or stepped and finite like tapswitch rectifiers,” says Dynapower’s Repairs Supervisor Remington Schieffer.
Let’s discuss two of our most popular industrial rectifiers: SCRs and SMPS units. A silicon-controlled rectifier (SCR) is a semiconductor power supply that meters electricity by opening electrical “valves,” working together as a team, to rectify electricity. The longer the “valve” is open, the higher the voltage leaving the rectifier will be.
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 running after 40 or 50 years. They regulate and react steadily, carry a lot of power in big copper windings, and are fairly easy to troubleshoot with large, easy-to-identify components.
A switchmode 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.
Switchmodes have been around for roughly 40 years. Traditionally, they were used in smaller current applications and it wasn’t until 10 years ago that large-scale switchmodes were successfully deployed.
Dynapower also designs and manufacturers high power IGBT chopper and thyristor rectifiers for large applications such as electrowinning, electrochemical, electrorefining, electroplating 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 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.
We can also discuss different types of rectifiers through the lens of cooling. When it comes to rectifiers, Dynapower’s mantra is that “Effective rectifier maintenance is good heat management.”
Rectifiers can be air cooled, water cooled, oil cooled and hybrid cooled. Traditionally, most companies will use air or water cooled rectifiers. Air cooled units are typically larger per watt of power because they need surface area to dissipate the heat while water cooled units are typically smaller because they don’t have to worry about surface area.
“Dynapower’s full fleet of engineers can purpose-design you a piece of equipment to fit your process, or your need or your footprint,” explains Scheiffer.
Rectifier Maintenance 101
How to Maintain Your Rectifier
When it comes to rectifier issues, a majority of breakdowns are due to electrical components overheating. For instance, if a circuit board heats up and the whole thing shuts down, it’s important to look at the actual root issue–which could be corrosion, bad cooling lines, or a wrong component put in during a repair. The point here is that any of those root issues can be measured and produce a significant amount of heat. And as we know, effective rectifier maintenance is good heat management.
“Being good at mitigating heat generation from all different sources is where the skilled technicians shine,” said Scheiffer.
For instance, some common causes of poor heat management could include the corrosion from circuit boards not being maintained, poor system cooling, breakdown of organic varnish in the transformer or poor bussing connections.
The general rule of thumb is: clean, flat, tight.
- If contacts are clean they will not have an opportunity to generate heat.
- If electrical surfaces are mounted flat to one another they will not have an opportunity to generate heat.
- If electrical surfaces are tight they will not have an opportunity to generate heat.
As we’ve outlined, heat is what destroys equipment.
“If you manage you’re heat properly your rectifier will outlive you,” states Scheiffer. “The half life of an SCR in 2010 is 75 years. Theoretically, an SCR rectifier should outlive everyone reading this article.”
Therefore, when considering the addition of a new line or process at your facility, taking the time to pick the right equipment and maintenance plan will save you some serious headaches in the future.
Finally, it’s very important to ensure you are hitting all the local and national safety standards as well as industrial and electrical codes when it comes to planning the lifecycle of your rectifier. In other words, you need to ask yourself: If your piece of equipment isn’t able to be worked on safely or be around, what’s that risk worth to your company?
What Sets Dynapower Apart?
Why is Dynapower the #1 Rectifier Manufacturer in the World?
The Dynapower Difference
We are your one-stop shop for everything rectifiers. Our experience and knowledge in the power systems industry is literally second-to-none. Combine that with our comprehensive aftermarket services and you’re in the best hands possible. In fact, with our experienced service team and rectifier training programs, we will do everything possible to maximize your uptime while saving your business money.
Our products are designed to IEEE standards and used in research labs, the US military and worldwide customers alike. Our products are also known for their safety.
“We take the extra time and money to put human safeties and guards in the equipment that are way beyond the standard rectifier manufacturer but we consider to be a bare requirement,” states Scheiffer.
At Dynapower, our engineering staff can build you what you want completely custom and on-site at our 150,000 square foot state-of-the-art manufacturing facility. While many other companies simply stick with cookie cutter designs, we are proud to offer custom solutions along with the most diversification and documentation of any other manufacturer in the country.
“It’s truly amazing,” Scheiffer adds. “Even within our aftermarket services team we have more service techs than some companies have design engineers.”
Additional Rectifier Offerings
For customers looking to upgrade their favorite piece of equipment, Dynapower is proud to offer a wide array of engineering upgrades. Typically, we will work with a company to first identify areas of their process that could be improved by making adjustments to their existing equipment. These include items like safety fixes to ensure the unit is in compliance and that maintenance work can properly be performed on the unit itself.
When implementing our engineering upgrades, we harness our 50-plus years in the power supply business to bring you the best possible upgrades for your systems. These include improvements such as extra thermal sensors, water pressure check valves, fan sensors, flow sensors, chemical contamination sensors and much more.
To cap it all off, Dynapower is proud to offer Touchpad, Touchscreen and Mutli-Unit Controllers. Our Touchpad Controller can be easily integrated into both silicon controlled rectifiers and switchmode power supplies. These controllers give you the ability to make precise voltage adjustments, pulse duration, cycle time and dwell time.
If you’re looking for the absolute best in terms of engineering upgrades then look no further than our Touchscreen Controllers and our brand new Multi-Unit Rectifier Controller. These devices are easily integrated into SCR rectifiers and offer users the ultimate control over their power supplies. The Multi-Unit Rectifier Controller can control between one and ten rectifiers from a single user-friendly touchscreen. This powerful controller also features a data logging system that allows you easily accessible downloads and record keeping as well as the automation of recipes, fault diagnostics and data logging of multiple rectifiers from a single touchscreen.
Preventative Maintenance Plans & Field Service
Dynapower stocks a wide variety of rectifier spare parts for all of your maintenance needs. These include items such as power supply control boards to regulate power supply current and volatage output, thermal switches, all types of fuses from fast acting to low-voltage 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 the part you’re looking for.
Dynapower also offers field service and preventative maintenance services not only for Dynapower and Rapid Power Technologies equipment but also for most other rectifier manufacturer’s equipment. Our field service includes commissioning, repairs, routine maintenance and equipment evaluation.
Dynapower’s four levels of 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.
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 full cleaning and reassembly of the entire power system from top to bottom. You do not have to own a Dynapower or a Rapid Power rectifier to take advantage of our rectifier refurbishment program.
Benefits of Rectifier Refurbishment
- Save 30% to 60% from buying new while gaining improved reliability, efficiency and safety.
- Longer equipment life, which includes complying with current safety standards and codes.
- Integrating modern parts and controls to improve ease-of-use.
- Standardized maintenance.
- Smaller environmental impact.
While we are happy to provide on-site rectifier assessment, Dynapower also offers a complete in-house refurbishment process with our state-of-the-art industry-leading test equipment. We use return merchandise authorization (RMA) to ship and precisely track the unit for testing to our facility. Depending on the process and availability of units, we also loan rectifiers to customers who do not have backups. In some instances, we will cover the costs of freight, and in every case, we provide a timeframe and options for repair to our customers. Go here to learn more about our rectifier refurbishment program.
Finally, Dynapower is proud to offer a low-interest financing program for our power supply systems. Through a partnership with Lease Corporation of America, we are able to provide you with a financing program that allows you to get the equipment you need NOW. And through IRS Section 179, you could see thousands in potential savings by deducting 100% of the cost of your purchased equipment in the first year that it is put to use.
Rectifier Financing Benefits
- Get the equipment you need NOW – pay for it over time
- Conserve your working capital
- Simple application and approval process
- Thousands of dollars in potential tax savings under IRS Section 179
- Let the equipment help pay for itself through its use
- $1 purchase option allows you to own the equipment at lease-end
For more information go here or contact us today at (802) 860-7200