Project Purpose:
Theatrical Install. The Company would like the ability to remotely turn off each Circuit of LED House Lighting. The lights themselves will be DMX controlled but they would also like to be able to physically power off the fixtures.
At $110-$160 a circuit for the MidAtlantic. it could add up fast. So far they have request 60 circuits over 3 installs. Also, with MidAtlantic, there is no ability for DMX control.
My Goal:
Use 1 Arduino Mega to Control Centrally Located 120vac 30 amp Relays on each install. Each Lighting Circuit gets 1 SPST Relay and a control Pin form the Arduino. Then tie this in via DMX, Ethernet and physical control line for various control needed for each install.
I did a retro fit of this exact system in an old building. They had 277vac Solenoid controlled lights. We did Ethernet with Web Interface, RS-485 via DMX and ability for hardware buttons. It has worked great.
My Challenges:
I'm having a hard time finding a suitable 120vac 30 Amp Relay. I want to 'Over Spec' the Relay incase some day they decided to plug a Motorized fixture into the circuit.
My guess is there are no Coil Based Relays in this category that can be Controlled via a 5vdc control voltage. I'm willing to build step up circuits. I hope to find a SPST 120vac 30 amp relay with 24v or less control voltage. AC or DC is OK on control.
I haven't had a lot of experience with SSRs so I have no idea if they would be a fit for this type of project or not. I do not like that when i have used SSRs they "bleed" a little voltage through the circuit even when off. For this reason I typically lean to Coil-Based Relays
Thank you for any suggestions or project guidance.
I have used many of these relays on both motor and resistive loads with no problems what-so-ever.
This is excellent! Thank you. What is your recommendation to get the 200 ma/channel required to power the coil? I don't need a step-up circuit like I did for the 24vac but I'm not sure what the most efficient method is to get the 5vdc 200 ma.. Mosfet? Darlington Array?
Also, Is there a Package version of these relays that does not need to be mounted on a PCB?
If I'm understanding the Spec Sheet, This relay is only rated for 15 A (1 HP) at 120vac. Is that really accurate or am I reading it wrong? If it is, then this Relay won't actually work. Hopefully I'm just mis-understanding the spec sheet.
What about this relay? Runs on 12vdc Coil. I can power both the Arduino and the Relays via a 12vdc PS. It shows to be a package and rated at 30 A at 277vac... I have no Idea how many amps that translates to 120vac though? Any idea how to know?
Nothing to translate. For Form A contacts (N.O.) the maximum contact power rating only occurs at max volts and max current.
30A (maximum switching amps or continuous amps) at 277VAC (8310VA) or less.
30A (maximum switching amps or continuous amps) at 28VDC or less.
At 120VAC, max current is still 30A, max power = 3600VA.
dlloyd:
Nothing to translate. The maximum contact power rating only occurs at max volts and max current.
30A (maximum switching amps or continuous amps) at 277VAC (8310VA) or less.
30A (maximum switching amps or continuous amps) at 28VDC or less.
At 120VAC, max current is still 30A, max power = 3600VA.
Excellent! Thank you! Looks like I may have found a very good fit for this setup.
A good quality solid state relay only has about 10mA leakage max, which would be nothing for a lighting application. There are many companies who make them, just Google it. When installed on to a heat sink, they are sometimes called solid state contactors.
The solid state relay has no coil, so it only needs 4-8 mA for a control signal.
A solid state relay is completely silent so they work well in theatrical applications.
Most solid state relays are "zero crossing", so they turn ON or OFF at the zero mark on a sine wave. This means that they will not create electrical interference that might be picked up on body microphones or other RF equipment.