Create a Checklist


Create a Checklist

You should create a checklist to keep track of everything that you are going to test. Relay testing should be more than pickup and timing tests.

Click “Mark Complete” below after watching the video so you can keep track of your progress.

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Can I get a copy of your checklist in excel. This is a great check list and I want to use it as a baseline for testing purposes.

Joshua Liuga Suiramo February 3, 2021 at 11:45 am

Few questions on : Create a Checklist

1. What is the purpose of the LT test?
2. where is the virtual relay is actually located?
3. With Output checks, what are some examples of this?


Chris Werstiuk (Administrator) February 3, 2021 at 12:05 pm

The LT test made sure the latching logic worked.
The virtual relay is a virtual piece of logic inside the relay.
Output checks make sure that the correct elements are mapped to the correct outputs.

All of this will be covered in future lessons.

Chris, is a latching relay and a seal in contact considered the same thing – just using different terminology? Is the latching relay in digital relays the new version of the seal in contact associated w/ electromechanical relays? Thank you

Chris Werstiuk (Administrator) August 26, 2021 at 7:52 am

They are functionally the same, but have different applications and operating characteristics.

A latching relay is a kind of control relay that can be a physical device or virtually embedded in a digital device. The latching relay will have a latch input (SET1) and a reset input (RST1). If the latch input is ON or True, the relay’s output contacts will operate and remain in the operated condition until the reset input turns on or is True. The functional drawing below looks like the seal-in circuit I’m about to describe below, but the latching relay has it all self-contained instead of using different devices. If it helps, physical latching relays will have a mechanical catch that traps the coil in the operate position once it operates. The reset input operates another relay that releases the catch and lets the coil open.

The most common seal-in circuit can be found in a motor starter control circuit. A normally-open start button contact (START PB) is is series with a normally-closed stop button (STOP PB), which is connected to a relay (S). When the start button is pressed, the relay operates a contact (S) that is in parallel with the start button, which keeps the relay energized. The relay is de-energized when the stop button is pressed. Same functionality, but the relay only has one input.

Motor Control Seal-In Circuit

A latching relay output contact will remain closed after a trip until a reset command is issued. It could use either of the two techniques above.

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