Torqued and Tested

Posted on 3/30/20 3:25 PM

Hospital-grade cord drop test

A Brief Overview of Interpower®’s Testing Capabilities

Whether it’s customized cord sets or electrical components for global industries, Interpower’s cords and cord sets are rigorously tested—again and again. And not just to meet UL and IEC standards.

“We test more than is required for our own benefit,” Product Development Manager Ron Barnett says. Barnett has been with the company since 2005. “The standards, such as the one for the UL 2556 Vertical Flame Test, are bare minimums. We go beyond the standards because it lends better reliability to our design—products become more reliable in that regard.”

The Interpower Testing Laboratory is located in Ames, Iowa, and is ground zero for the majority of critical tests that determine whether Interpower products such as cords, plugs, sockets and power strips (along with a variety of specialized electronic components) meet or exceed North American and International standards.

“Some products we test more often than others due to the volume we manufacture, such as our line of C13 cords and cord sets,” Barnett says.

UL 817 Abrupt Removal Test

In this test, hospital-grade plugs are attached to a 10-lb weight that is dropped to pull apart the connections to see how far the blades have bent, and to see if the wires have been pulled out of the crimp or broken crimping has been pulled away from the wires.

UL 817 Abrupt Pull Test

The Abrupt Pull Test features a typical NEMA 5-15 plug, not a hospital-grade plug. A 2 ½ pound weight is dropped 25 times from the plug. At the start, three lights on the test equipment glow red showing electrical continuity However, during the test, if one of the three wires fails (line, neutral, and ground) and one or more lights go out, the test is considered a failure. If that occurs, the plug is examined to see why the continuity was broken.


Temp-Rise Station

In this test, thermocouples attached to components of electrical contacts measure temperature rise. The thermocouples are soldered onto the blades of the plug or connector so the temperature can be monitored when connected to a power source—how fast did it rise? By UL 817 standards if less than 45° Celsius the test is successful in North America. For International Standards such as IEC 60320 and IEC 60884, that margin of error is 30°. A reading is taken every minute as a computer program charts the rise in real time. If the temperature is found to rise too quickly, subsequent testing ensues to discover the faulty component(s).


Crimp Cross-Section Test

This is an in-house Interpower test. The crimp barrel is cut in half, polished, and then washed in acid to get the smoothest finish possible before testing. Then, the crimped section is photographed under a microscope. The two rounded protrusions of the crimp are called “barrels.” The crimp is composed of several strands of wire, and must be tight enough to maintain contact. New crimps off the assembly line are randomly tested at all manufacturing locations. While a good crimp means a good connection, a poorly crimped cord may cause a fault or a rise in temperature.


Heat and Humidity Chamber

Temperature standards related to component material and function are reasons the Interpower testing lab maintains a Heat Chamber. A heat test may last 8 hours or 24.

Breaking Capacity and Normal Operation Test

The Breaking Capacity Test produces arcing as the connections are “live” when they are inserted or pulled apart. The testing machine has a shield which protects the test personnel from severe shock. One purpose of this test is to see whether arcing tracks along the plastic, which could cause damage to the component, or worse, a fire.

Vertical Flame Chamber Test

If a cord burns longer than 60 seconds it’s a fail. Also, a paper flag hangs along the cord inches above the flame. “If the flame burns more than 25% of the paper flag, that’s a fail,” Barnett says. “We test as many cords as we can since a greater sampling of cords means better data.”

International Testing Agencies Wall Chart

Topics: testing, designing for export, safety, compliance standards, USA Made Products

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