WARNING
Make sure the whole control station is not energized before touching or starting your exercise!
Objective
Learn how to wire 24V DC pilot light with push buttons to turn it on/off along with latching of an encapsulated relay.
Material
Multimeter
AC/DC power supply. Input 120V AC and output 24V DC, 1A (at least)
Push button (green )
Push button (red)
Pilot light (green). 24V DC
Encapsulated relay with coil of 24 VDC
What to do
For this exercise, one of the NO contacts of the relay shall be used for latching, with 24V DC, and the other one for turning on the bulb light.
Connect the encapsulated relay coil terminals (A1 and A2) after the start button
Connect one of the normally open NO encapsulated relay contacts (say 24 and 21) in parallel with the start button
In rung 1. Connect the other normally open NO encapsulated relay contacts (say 14 and 11)
In rung 1. Connect the pilot light after the relay contact (14,11)
If you omit connection of the pilot light a short circuit could occur as well as damage to the equipment
Set on the power supply
Use the following ladder diagram:
 |
| Fig. 01 Ladder diagram to turn on/off a pilot light and keep it on by latching an encapsulated relay. |
- The pilot light should turn on when the start button is pushed and keep in this state
- The pilot light should turn off when the stop button is depressed
- Check for continuity if needed
How to do it
For this exercise the same setup developed for LE 03 is to be used. Details shall be omitted and refer to LE 03 for more information.
Step 1. Identification of the encapsulated relay
There are several configurations of encapsulated relays of varying size, mounting, number and type of contacts, for example. The ones used for this exercise are the most common as shown,
 |
| Perspective view of an encapsulated review |
 |
| View of contacts in an encapsulated relay |
The encapsulated relay has a typical contact configuration as follows,
 |
| Detail of terminal connections in an encapsulated relay |
 |
| Diagrams of connections in an encapsulated relay |
 |
| Connection site of an encapsulated relay |
Step 2. Identification of the pilot light
The pilot light has two terminals only labeled as X1 and X2 as shown,
 |
| Side and bottom view of a pilot light |
 |
| Side and bottom view of a pilot light |
Step 3. Energizing the loop
In order to power the loop you should activate the circuit breaker to the ON position with the lever upl and the green indicator being shown.
 |
| Thermal circuit breaker |
Step 4. Continuity and DC voltage test
Check for continuity at every contact and for 24V DC using the multimeter. Since you are using a power source for 24V DC you should get a reading not far from this value.
Continue your training with the next exercise
Any question? Write in the comments and I shall try to help.
No comments:
Post a Comment