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Abstract—Testing is the last line of defense for relay system

performance before the switch is thrown. The power supplier

must be assured the system will protect for all possible faults,

over- and undervoltage, and other actionable conditions under

continuingly varying system status. The power supplier must also

be assured the protective system will not generate false trips or

overtrip, causing undue outages or other adverse power quality

conditions for its customers. Installing a relaying system,

performing basic tests, and then hoping for the best is no longer

an acceptable way to do business in light of problems that have

occurred in the last few years. The relaying system must be

“dialed in” before the line is energized.

Throughout the power industry, there are a variety of

philosophies on testing relays that vary from basic go/no-go tests,

to power system simulation, to installed system end-to-end tests.

We will explore these various methods by compiling field testing

experience and comparing the results achieved. We will analyze

how many potential problems were found with equipment, relay

settings, relay logic, or other things.

Modern relays provide sophisticated logic to provide

traditional functionality but can be used to provide more

complex custom control. The typical engineer does not have the

means to reliably test programming from behind the desk. These

tests are normally performed in the field. Training and guidance

are needed for engineers and technicians so they can develop

comprehensive and fool-proof tests to ferret out any potential

problems.