Turbo 200 Capacitors

NOTE: - This is a re-posting - I got Mona's e-mail wrong on the first one.
Have you ever had to replace a dual capacitor only to find you do not have the right one on the truck? There are so many different possible combinations it is nearly impossible to have every one you might need. Amrad Engineering makes capacitors here in the USA. They make replacement capacitors which have a wide range of capacitors built into a single part called the Turbo 200. With these, it is possible to replace most any dual capacitor you need. These capacitors are great for teaching students about series and parallel capacitors. Basically, the Turbo 200 is 6 capacitors connected together at the center post. Any two outside connections are essentially in series. Measuring the microfarad between any two outside terminals shows the effect of capacitors wired in series. Jumping any two outside terminals puts those two capacitors in parallel. Placing a jumper between any two outside terminals and measuring the microfarads between either outside terminal and the center terminal shows how capacitors connected in parallel work.  Amrad engineering is offering a free kit to all HVACR instructors. They want to send out a kit of their products with instructions to schools all over the country to promote their products. The stuff they sent me was fantastic. Here are a couple of pictures of the kit.

To get a kit for your school contact
Mona Tompkins Amrad Engineering
1-800-445-6033

mtompkins@yahoo.com

Summer is Capacitor Replacement Season

Any practicing service tech will tell you that service calls involving dead capacitors are common, especially in hot weather. The two most common causes of capacitor death are heat and over voltage. However, there is another less known cause: old age. Many capacitors have a shelf life. I have seen shelf lives listed as little as one year. The oxides on the metalized film break down when the capacitor is not in use, weakening the capacitor. They do tend to self-heal during use. That is why a capacitor which cannot sit on the shelf for longer than a couple of years can last for ten years in use.

Always check the capacitance of any replacement capacitor with a capacitor tester or the capacitance scale on a digital multi-meter before using the capacitor. It may have already died of old age before you install it! A capacitor is a pretty simple device, basically, it is a couple of rolled up sheets of aluminum foil or metalized film with paper or plastic between them. Although a capacitor is a simple device, it is an extremely important part on most air conditioning systems. A bad capacitor can kill a system’s compressor. To protect your reputation and your customer’s equipment, only use capacitors that can pass the EIA-456 Highly Accelerated Life Test. The HALT test subjects a set of capacitors to 125 percent of their rated voltage and 10˚C above their rated temperature for 2,000 hours. For example, a capacitor that is rated at 5uf/440 vac, with an operating temperature of 70˚C, is tested at 550 vac and 80˚C for 2,000 hours.  

Determining which capacitors to stock on your truck is another problem. There are so many sizes of dual capacitors that it is nearly impossible to have all the necessary sizes. American Radionic, AMRAD, has a solution – a multiple capacitor with enough sizes to cover nearly any application. Better yet, they will send instructors sample capacitors to use in your lab. These are great for demonstrating the effect of connecting capacitors in series and parallel. Their web site is AMRAD

Fundamentals of HVAC/R 2nd edition has coverage of capacitors and their effect in circuits in Unit 34 Alternating Current Fundamentals, Unit 37 Electric Motors, and Unit 88 Troubleshooting Refrigeration Systems.

Are Your Capacitors Stale?

A capacitor is a pretty simple device, basically a couple of rolled up sheets of aluminum foil or metalized film with paper or plastic between them. Any practicing service tech will tell you that service calls involving dead capacitors  are common. Technicians that have been around for a few decades will also tell you that capacitors die a lot more now than they did twenty years ago. This is because the newer capacitors use a different electrolyte. The electrolyte in the “good old style” capacitors was polychlorinated biphenyl, PCB. PCB causes cancer, so it is no longer used. The newer capacitors are smaller and less expensive than the older PCB capacitors, but they are not as robust. The two most common causes of capacitor death are heat and over voltage. However, there is another less known cause: old age. Many capacitors have a shelf life. I have seen shelf lives listed as little as one year. The oxides on the metalized film break down when the capacitor is not in use, weakening the capacitor. They tend to self-heal during use. That is why a capacitor that cannot sit on the shelf for longer than a couple of years can last for ten years in use. 

Always check the capacitance of any replacement capacitor with a capacitor tester or the capacitance scale on a digital multi-meter before using the capacitor. It may have already died of old age before you install it! Although a capacitor is a simple device, it is an extremely important part on most air conditioning systems. A bad capacitor can kill a system’s compressor. To protect your reputation and your customer’s equipment, only use capacitors that can pass the EIA-456 Highly Accelerated Life Test. The HALT test subjects a set of capacitors to 125 percent of their rated voltage and 10˚C above their rated temperature for 2,000 hours. For example, a capacitor that is rated at 5uf/440 vac, with an operating temperature of 70˚C, is tested at 550 vac and 80˚C for 2,000 hours. Two links for more detailed information on capacitors are  

Aerovox

Genteq

Determining which capacitors to stock on your truck is another problem. There are so many sizes of dual capacitors that it is nearly impossible to have all the necessary sizes. American Radionic, AMRAD, has a solution – a multiple capacitor with enough sizes to cover nearly any application. Better yet, they will send instructors sample capacitors to use in your lab. These are great for demonstrating the effect of connecting capacitors in series and parallel. Their web site is AMRAD

Fundamentals of HVAC/R has coverage of capacitors and their effect in circuits in  Unit 29 Electrical Power and Circuits, Unit 30 Electric Motors, Unit 33 Control Circuits, and Unit 83 Troubleshooting Refrigeration Systems. Unit 30 of MyHVACLAB has an interactive exercise on determining capacitance and a video on testing capacitors. Unit 83 has an interactive exercise on testing capacitors.