Timers and Smart Relays. Flashcards Preview

Electrical Lab MCSC Period 2 SAIT-Alberta > Timers and Smart Relays. > Flashcards

Flashcards in Timers and Smart Relays. Deck (11)
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1

What are the three basic types of timing devices?

Spring-wound interval timers.
Mechanical and electronic time switches.
Timing relays.

2

Is a spring wound interval timer used when precision of timing is required?

No, it is not very accurate and inexpensive.

3

What are mechanical and electrical time switches generally used for?

Security lighting control.
Landscape irrigation.
Parking receptacle circuits.

4

How would one adjust a panel mount timing relay?

Timing is adjusted by connecting the appropriate resistors to terminals on the relay.

5

What are the two basic timing functions a relay can provide? There are three additional functions used by a multi-function relay, what are these?

Time delay on energization (TDOE),
Time delay on de-energization (TDOD).

Interval,
One - Shot,
Repeat cycle.

6

If an interval relay was started and the relay lost power, would the timing interval be interrupted?

Yes, the timed contacts would immediately open. Generally speaking, a timing relay requires power to keep the contacts energized.

7

Which function, always utilizes an initiating circuit with dry contacts?

One - shot.

8

What must be used in any basic TDOD circuit?

A mushroom stop button, to maintain safety.

9

How must a smart relay input be connected?

The input simply registers voltage for the internal programmable contact to close. This may be interrupted by a pushbutton or switch to serve as the input.

10

How does a smart relay output work?

A smart relay output is simply a set of normally open contacts which close, when the path of the ladder logic program allows it.

11

Are smart relays generally more advanced/useful than timing relays?

Yes, they are fully programmable and have an abundance of timing functions.