Rectifiers are power systems that convert alternating current (AC) to direct current (DC) power. The applications in which rectifiers are used are seemingly endless—with everything from metal finishing in the automotive and aerospace industries to mining, military defense and waste water treatment.
When it comes to purchasing a new rectifier or determining if it would be more cost effective to upgrade or refurbish, there are three main areas to consider: Process, environment and people.
Often, customers get lost in questions such as: Air vs. water-cooling? Switchmode or SCR type? Manual controls or PLC?
Like anything else in life, the more you put into researching and understanding the type of rectifier you need and more importantly why you need it—the more successful your operations will be.
It’s imperative that you take a step back and identify the criteria for your current process and if that process will be expanding in the future. You need to evaluate the location and area surrounding your location as well as your operator’s skills and availibity.
But in the end, it all comes back to the same three considerations: process, environment, and people.
Consideration #1 When Buying a New Rectifier: Process
Perhaps the most important question you can ask yourself is: What’s your process? This includes figuring out how much time your equipment needs to be running to hit your production requirements. Another way to make this determination clearer is by using TAKT time—which is the average time between the start of production of one unit and the start of production of the next unit, when these production starts are set to match the rate of customer demand.
“In other words, do you plate 19 hours a day or does the line run 9 months out of a year,” points out Remington Schieffer, Dynapower’s Repairs Supervisor. “For instance, zinc plating shops that produce scrap don’t run good product 24-hours a day. They may run sixteen hours and spend the other eight doing cleanup, maintenance, or stripping and rerunning parts.”
Another important point to consider as you evaluate rectifiers is determining your reporting requirements. Do you need to see real-time voltages and amperages? Do you need to see how much current is running into the different sections of the tank? Do you need to see the real-time ripple to verify power quality as it applies to your process?
Finally, it’s critical that you evaluate your customer or corporate requirements as well. What do they need to see as it applies to the considerations above? What accuracies or level of control are their technical standards requiring? Do they look for testing, calibrations and PM schedules on your equipment that are critical to your process?
After all, your customers are trusting you with their hard work and parts. Once you have these basics on your process requirements nailed down, you’re ready to take the next step in purchasing your new rectifier.
Consideration #2 When Buying a New Rectifier: Environment
What is the air quality in your production environment? This is especially important if you’re considering purchasing an air-cooled rectifier.
But did you know air quality can choke the life out of your new water-cooled equipment? Air heating and cooling around the transformer and water lines can change the rectifier cabinet’s internal air pressure and lead to some surprising air consequences.
“Not all water-cooled rectifiers are created equal,” Schieffer adds. “And not all rectifiers are fully sealed. Many of them are built with holes in the bottom as part of the frame and actually breathe like a lung [when they thermal cycle for cooling]. ”
There are three main types of cooling for rectifiers: water-cooled, air-cooled and oil-cooled. When it comes to water-cooling you need to determine whether you can handle the heated water generated in your process or will you need to send it to the sewer? Some companies have found unique ways to reuse their water from the rectifier cooling loop in their process.
On the opposite end, if you’re leaning toward air-cooling, you need to weigh the humidity and chemical exposure in your shop since this can degrade equipment quickly. Meanwhile, oil-cooling rectifiers are sometimes chosen because they are sealed off from the environment, but can be costly, logistical nightmares. Ultimately, it comes down to the facility the equipment is in and what resources your team has to work with.
The humidity in your work environment is also a very important piece to understand. If the air particle contamination is poor enough, then any chemistry in the tanks will be deposited around the rest the equipment. The chemistry is not the most dangerous part of the facility. Dry acid salts have limited conductivity. However, once they are dissolved into water, they make dangerous arc paths in your equipment.
“If there’s condensation on the walls then there is condensation on/in your rectifiers. That condensation activates the chemistry that has deposited on the rectifier and you start actively rusting your equipment,” states Schieffer.
This fact is important for switch mode power supply rectifiers since the parts and fixes are much more susceptible to chemistry and damage if you’re not planning ahead for your new rectifier. “Humidity should be a separate consideration from air particle contamination because dust is manageable,” Schieffer says. “Humidity exacerbates the air particle problem to equipment failure.”
Next, you should consider line hazards that could affect the operation of your new rectifier—which, in turn, will influence the type and set-up of your new power system. “You need to plan your equipment around line hazards and vice versa,” Schieffer points out.
You also need to ask questions like: Where’s the acid tank going to splash? Do you have an overhead crane that can drop it’s load? Do you have forklift traffic nearby? Where’s your arc flash barrier? Is the rectifier going to be beneath water lines that could potentially drip from condensation?
Another important but often overlooked concern is safety. For instance, if your facility sees a lot of forklift or overhead crane traffic, you will probably want to avoid going with an air-cooled rectifier due to safety concerns. You’ll also want to ensure that the new power system complies with your company’s safety policy. This includes both the safety of the people working on and near the equipment but also of the equipment itself.
“It’s imperative that you know what you need so your guys can work on the rectifier safely,” Schieffer adds. “Not all equipment is built with common sense. Some equipment is not even built with safeties.”
To sum up, the more you know about your equipment, the better your results will be. At Dynapower, we pride ourselves as being a proven leader–both in terms of product quality and safety–in the power systems industry since 1963.
Consideration #3 When Buying a New Rectifier: People
Finally, you need to consider your people. First, let’s discuss man power. How much qualified manpower do you have to put toward the upkeep of your rectifier? This includes tasks like changing air filters, checking water strainers, chemically cleaning the equipment and other preventive maintenance.
It’s also important to have a good idea what the knowledge pool is around the people on the floor and those interfacing with the equipment. In other words, can your business handle working on the rectifiers internally or will you need outside support?
This ties in with overall planning. Is your planning done internally or externally? “If you rely on external people to plan for you, you are taking a risk. If you are relying on outside input for any reason other than manpower, you know you need a recommendation but may not know enough to evaluate that recommendation,” Schieffer points out.
At Dynapower, we offer a complete aftermarket service—including spare parts, onsite repairs, preventative maintenance, and training programs each delivered by a team dedicated to the uptime and longevity of your rectifiers, and your success. As always, our 24/7 technical support is available free of charge.
“We also offer the opportunity to come and help install the equipment with you,” Schieffer says. “We’ll look at what you did and verify that everything is set up correctly.”
By understanding your process, environment and people, you should have no trouble finding the rectifier that is best suited for your business goals.
