Switching 50 Relays at same time !

[Jaikanth.V]

Hi,

I have 50 relays.

230V are connected to NO terminals.

I need to switch all 50 relays same time so that 230V output i will get from them.

Actually speaking i want to switch 5 mins ON and 5 mins OFF sequentially.

the 230V will be in parallel connected to all relays.

If i go for timer, i do not know how one timer can switch all 50 relays same time?

thanks.

 

[wkrug]

I think that wouln't work proper.

Even using for all relay the same type, some contacts will be closed faster then others.
So the first closed relay get the full current of the load an will be broken very fast.
At opening of the relays the same problem occurs.

To drive 50 relay with DC Coil, you can use a power Mos Fet. Don't forget the free-wheel diode at the relay coils.

When the relay coil is a 220V AC type, you can use a additional relay to drive all the other relays or a Solid State Relay.

 

[Jaikanth.V]

Hi wkrug,

Thanks for the info.

Where can i get tutorial on this below subject ?

"To drive 50 relay with DC Coil, you can use a power Mos Fet."

thanks.

 

[Reloadron]

It sounds like what you want is a repeat interval timer. You can buy a plug and play solution like this one for an example, they are common and made by a wide range of manufacturers, or you can build your own using a circuit along these lines. There are much less expensive timers out there as a ready made solution also.

You want to be switching 220 VAC using 50 relays but you don't mention the current you want to switch, 220 VAC at what current and will the load be inductive or resistive?

As wkrug points out, all relays will not switch absolutely simultaneously. There will likely be a few milli-seconds lead/lag between the relays. You mention the relays will have a DC coil but no mention of the DC coil voltage or coil current for the relays? Yes, a MOSFET or just about any switching transistor can turn a DC coil relay off/on but you really need to provide the data sheets for the relays you plan to use. Additionally you may not need a mountain of MOSFETS. Since you mention 5 min ON and 5 min OFF (then repeat) how critical can a few milli-seconds be?

If you could better explain exactly what you want to do and what the loads will be I am sure you could get better help.

Ron

 

[KeepItSimpleStupid]

Hmm. I think the OP wants:
turn on relay 1
wait 5 min
turn off relay 1; turn on relay 2
wait 5 min
turn off relay 2; turn on relay 3
.....
turn off relay 50; turn on relay 1
Repeat ?

"Sequential" and "at the same time" are mutually exclusive.

Am I right?

 

[ljcox]

Hmm. I think the OP wants:
turn on relay 1
wait 5 min
turn off relay 1; turn on relay 2
wait 5 min
turn off relay 2; turn on relay 3
.....
turn off relay 50; turn on relay 1
Repeat ?

"Sequential" and "at the same time" are mutually exclusive.

Am I right?

This is a good point.

One wonders why you would want to switch 50 relays simultaneously (or near to simultaneous given the small variations in operate time between relays).

 

[dr peppers]

The cheapest option to build such a circuit would be to use a microprocessor and some shift registers to produce 50 outputs, then each output used to trigger a triac to switch ac to the coil, or as mentioned a fet if the coils are dc.

Or if you dont have the experience to build such a circuit, you could use standard on delay timers (there are different modes available), and use the output of one timer to trigger the next, triggering the first timer will start the cycle, much like a domino rally.

Industrial PLC controllers usually come with built in features for doing such things, a cam timer emulator is one of them, you'd specify 50 postions, then you have any output combination for each of the positions.

 

[Reloadron]

Actually reading it again I am not sure?

I need to switch all 50 relays same time so that 230V output i will get from them.

is where I saw at the same time and then ....

Actually speaking i want to switch 5 mins ON and 5 mins OFF sequentially.

Yeah, the sequentially? Oh well, guess we wait and see.

Ron

 

[ljcox]

The attachment shows the basic idea of how I would do it.

I would use a PIC to drive the address lines, but there are other possible solutions.

 

[Jaikanth.V]

View attachment 61561

i'm thinking to go as per the attached diagram.

 

[Jaikanth.V]

I'm sorry about the confusion caused by using the word "Sequentially" .

The scenario i'm looking for is as below:-

All 50 relays ON same time

wait 5 Mins

All 50 relays OFF same time

wait 5 Mins

This cycle repeats up to 24 Hours.

 

[KeepItSimpleStupid]

You pretty much have it nailed. The 5 min On/5 min off timers are off the shelf. If yu want something a little fancy you could use a small PLC or IDEC Smart relay. The smart relay can give you a small operator's interface. The programming software is freely downloadable and you can simulate what you need to see if it's suitable. I/O is limited.

 

[dr peppers]

Looks like a load test box for a generator.

The circuit looks acceptable, I'd reccomend that you use triacs to switch the 50 load resistors, and use zero crossing switching, you can get an opto isolator with zero crossing built in, it would be a lot cheaper and wouldnt generate nasty spikes every time one switches in and out.

 

[Jaikanth.V]

thanks dr peppers !

and thanks for all !