Circuit drawing of two floodlights with relays

In summary: Then use a primary and secondary winding on the transformer. This would allow you to use lower voltage lamps without damaging them. 500W is a bit much for a transformer.In summary, the author is looking for a way to connect two 500W floodlights in such a way that if the primary light dies out, the relay will connect the secondary light to the source. He has considered connecting an auxiliary relay in series with the primary light, and the relay's normal closed contactor in series with the secondary light. However, because the current drawn from the 500W floodlight is too strong for the auxiliary relay, he is unable to connect it in this way. He is also considering using a high power 2.5A LED in series
  • #1
Hrvoje
7
0

Homework Statement



I need to draw a simple electric drawing that will in reality present a circuit with two 500W floodlights connected in such a way that if the primary light dies out, the relay will connect the secondary light to the source. Only the primary light is supplied, while the secondary light is on the stand-by, waiting to be connected by the relay contactor in case of primary light dying out.

The Attempt at a Solution



I was thinking about connecting an auxiliary relay in series with the primary light, and the relay's normal closed contactor in series with the secondary light. In case primary light dies out the relay looses it's supply, closing it's normal closed contactor on the other light. But since the current drawn from 500W floodlight is too strong for the auxiliary relay it seems I can't connect it in this way.

I'm sorry but I'm writing this post from a satellite Internet connection from high seas so it's impossible for me to upload a drawing. Can you PLEASE post a drawing of the solution? If there is no way in creating such a circuit with relays only, can you please draw and explain which other elements the circuit would need.

Thank you very much.
 
Physics news on Phys.org
  • #2
If your relay cannot handle the current, you could try to bypass a part of the current (with a very small resistor in parallel? With more identical relays without mechanical use?).

Some more details about the floodlights would be interesting. Which voltage and current do they use?
Transistors could be interesting.
 
  • #3
Could you use an ordinary light sensor? The sort used to turn floodlights on at dusk? Just point it at the primary lamp. If that's working it will turn off the aux lamp. The need to keep the sensor clean is a dissadvantage.
 
  • #4
The floodlights use 220V AC power supply. With the power of 500W they draw around 2,2A.
The idea is to have auxiliary relays connected to draw as little Amps as possible.

There must be a way to do it. If needed, additional elements can be used in a drawing. Can you PLEASE help me out?
 
  • #5
Perhaps have a look at an "under current" control/monitoring relay which switches when the current is falls below a set value. Likely to be relatively expensive compared to a custom design but that depends on what your time is worth.
 
  • #6
Hrvoje said:
I need to draw a simple electric drawing that will in reality present a circuit with two 500W floodlights connected in such a way that if the primary light dies out, the relay will connect the secondary light to the source.
Simple? In theory you could take the thin wire off the core of a relay and replace it with thicker (low resistance, low voltage loss) wire that carries 2A to operate the relay. Not sure how practical that would be.

Or, maybe you could find a high power 2.5A LED and insert it in series with the cable feeding the floodlight, and proceed to fabricate your own opto-isolator. Parallel the LED with a reversed diode to handle the other half-cycles. Here's the idea: http://aristarco.com.es/sites/default/files/dual_relay1.png The circuitry will need its own low-power DC supply. Probably easier to add a small (e.g., 2Ω) series resistor, and operate an off the shelf low power opto-isolator.
 
  • #7
Could also make a small transformer by winding the wire feeding the main lamp around a ferrite.
 

1. How do I draw a circuit for two floodlights with relays?

To draw a circuit for two floodlights with relays, you will need to first determine the power supply for the circuit, the voltage and amperage required for the floodlights, and the type of relays needed. Then, using a circuit diagram software or by hand, draw a schematic showing the power supply connected to the relays, which are then connected to the floodlights.

2. What type of relays should I use for this circuit?

The type of relays you should use for this circuit will depend on the voltage and amperage requirements of your floodlights. Make sure to choose relays that can handle the necessary load and have the appropriate voltage rating. It is also important to consider the contact type (normally open or normally closed) and the coil voltage of the relays.

3. Can I use a single relay for two floodlights?

It is not recommended to use a single relay for two floodlights, as it may not be able to handle the load. It is best to use a separate relay for each floodlight to ensure proper functioning and to prevent overload on the relay.

4. How do I wire the relays for this circuit?

To wire the relays for this circuit, you will need to connect the power supply to the common terminal of each relay. Then, connect the normally open terminal of each relay to the positive terminal of the respective floodlight. Finally, connect the negative terminal of each floodlight to the negative terminal of the power supply.

5. Are there any safety precautions I should take when working with this circuit?

Yes, there are a few safety precautions you should take when working with this circuit. First, make sure to turn off the power supply before making any connections or modifications to the circuit. It is also important to use relays that are rated for the voltage and amperage of the circuit. Finally, ensure that all connections are secure and insulated to prevent any electrical hazards.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
34
Views
2K
  • Electrical Engineering
Replies
25
Views
2K
Replies
31
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
Replies
13
Views
2K
  • Electrical Engineering
Replies
25
Views
4K
Replies
37
Views
3K
  • Electrical Engineering
Replies
1
Views
765
Replies
12
Views
1K
  • Electrical Engineering
Replies
13
Views
3K
Back
Top