In - situ Electromagnetic Compatibility Testing On Large Electronic Equipment

One of the biggest problems facing engineers when EMC testing of large electronics is required is the inability to move the equipment that is being tested. When the equipment must be tested in-situ, the entire environment surrounding the equipment must be included in the process. The environment is a part of the system, meaning that they could be the source of problems that have led to the testing. It isn’t unusual for large-scale systems to require in-situ testing, particularly when a problem occurs after installation.

Many different scenarios can occur where installation of equipment results in interference from the RF environment. The only way to detect the source of the interference is to perform EMC testing while the equipment is in the place where it will be operated. Complications occur because of existing sources of electromagnetic energy that produces higher levels of radio frequency that are within the limits for the test. In many industrial situations, the radio frequency levels continually change, making it difficult for the person performing the test to determine what the equipment is responsible for and what is normal.

Sometimes the company performing the EMC testing will be required to access the equipment with equipment like a cherry picker or by lifting an antenna to the top. Even when the various parts used to install the equipment has previously met EMC standards, the equipment once assembled and in place may not. The reason for being tested is to determine if the assembly is compatible with its environment and with every part of the installation process.

Most of the time, a problem occurs after the installation of a new piece of equipment. Although even larger pieces of equipment or systems are determined to be sound prior to being installed, the reaction with the environment can cause unforeseen problems. Whether the equipment has been prototyped or a new system has been built to replace an existing one, the installation is usually complete or nearly complete by the time the problem is detected. At this stage of the implementation, fixing the problems is usually more cost-effective than changing the overall design.

Establish the Purpose of EMC Testing

Some determinations need to be made prior to the testing process. For example, is the equipment to be tested causing interference to the surrounding systems? Is it susceptible to an ambient EM signal or are you simply running a qualification test? Does the system pose a threat of radiation emissions to the employees in the area? You should also determine whether lightning or ESD transient interferes with its operation.

The reason that you are performing the EMC testing process will determine which procedure is used and what equipment is required. This is especially important when you hire a company to do the testing on very large electrical systems that may require special equipment. For those tests being performed in response to a problem, the goal is to create a system that is self-compatible and which performs its intended functions according to the configuration with which it is installed.

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