Week #14: IPC Standards, Megger & Hi-Pot Testing

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rjagodowski
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Joined: Fri Sep 04, 2015 6:59 pm

Week #14: IPC Standards, Megger & Hi-Pot Testing

Post by rjagodowski »

We'll begin this weeks discussion finishing up from Week #13 on shielding and EM Compatibility.

This week we will discuss various IPC standards and what you should be aware of when applying for a company that adheres to specific IPC standards. Here is the link to www.IPC.org.

We'll watch an IPC video on Safety in the Electronics/Electrical Industry posted in Week #14 of our Blackboard area. There is another posted in Blackboard dealing with "Wire Crimping". While soldering wires is a very common way of making good electrical connections, there are applications in which soldering is NOT used, and wires are "crimped" together instead. The crimping uses a purely mechanical method of creating a strong, reliable connection between a wire and a terminal. A properly crimped connection is stronger than a soldered connection, and can generally be done quicker than a soldered connection. Due to the increased strength crimped connections are often required in applications which are subjected to mechanical stress, vibration and heat. Here's a links showing Crimp vs. Solder, and it's pdf, if you prefer:
Ref-Crimp-vs-Solder.pdf
(759.08 KiB) Downloaded 103 times
Here's an example of what some of the issues IPC standards and certification educate and protect against:
Measles - Delamination - Crazing.pdf
(5.05 MiB) Downloaded 171 times
This document is from EPTAC (Electronic Process Training and Consulting), an internationally recognized solder training and IPC certification corporation. Here's the description of their Hand Soldering Certification.


Taking a little detour, here's some history about a company known as Keysight Technologies. In 2013, Keysight was a spinoff division from Agilent. Back in 1999, Agilent was a spinoff division from Hewlett-Packard (HP), a maker of electronic test & measurement equipment, which had its first product in 1938. THAT part of the business is what is now called Keysight. Now, HP is predominantly an IT based company for hardware, software and IT infrastructure support. Agilent, since Keysight was spunoff in 2013, focuses its products and services in the following industries: food, environmental, forensics, pharmaceutical, diagnostics, chemical, energy and research.

All of the above as background that Keysight is using IPC-2591 Standards in their roadmap to introduce and implement Smart Factory, Industry 4.0 & IoT/IIoT technologies. About IPC CFX.


We will then finish up discussing two pieces of test equipment not used in our curricula, but which have use in certain electrical and electronic areas. These are the Mega-Ohmmeter (Megger) and the High Potential (Hi-Pot) tester. They perform related tasks but in different ways. They both test the insulation resistance.

Back in Basic Electricity 1, you learned about the ampacity of various wire gauges, and the resistance of wires based upon their cross-sectional area. Larger cross-section, less resistance/unit length. Very little discussion was made about the insulation used on these wires. The obvious purpose of the insulation is to keep the electric current within a conductor contained to that conductor only. But somewhere along the line, the concept of "dielectric strength" should have been introduced as well. Dielectric strength is voltage potential at which an insulator can no longer insulate, as it will "break down" due to the electro-motive force of the voltage. So wire manufacturers select the type of resistance used for a wire based partly upon the dielectric strength the wire must have. (If you've ever seen a spark-plug wire, you probably noticed it's a very thick wire. It is thick due to the insulation because the voltage in spark plug wires is usually measured in the 10's of thousands of volts. In order to contain that voltage, a very thick insulation is needed, but the current is small, so the conductor is pretty thin (small cross section). Compare this to the cables connecting to your car battery. Those cables are very thick as well, but in this case it's due to the large cross-section of the conductor because that cable often has to carry 100's of amps of current. However, the voltage is low (+12V), so minimal insulation thickness is needed to "contain" low voltage. )

The Mega-Ohmmeter Testing is used to measure the insulation resistance of an electrical system/component/wire.

How to Measure Insulation Resistance with a 1587 Meter.

Testing a 3-phase motor with a Megger. (3:49)

Hi-Pot Testing is used to stress the insulation and if there is a weakness to induce a failure. That is, the Hi-Pot testing is used to "stress test" for a failure so that it can be repaired before it's put back into service.

How to use a Hi-Pot Tester. (5:21)

Hi-Pot vs. Megger
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