Hello.
I require a relay which can switch 72VDC.
DC is the important part. As most seem to maxc out a 30VDC as I know its harder to switch.
So my setup is Arduino Leonadro, 5V switching signal to the Relay.
The Relay then switches a 72VDC load on/off. Just for 50ms. The current is also very low as its just moving a solenoid.
This is currently working with an all in one hobby relay board with Songle 30VDC/240VAC relay, but concerned about the longevity.
I'm ideally looking for an all in one solution , so relay already mounted on a board with terminals and optocoupler etc.
Alernatively, will a MOSFET board of some kind do this? Im cluessless about those.
You didn't specify the current.
If you want something reliable for higher currents, go with quality DC SSR.
If you current is low, you can try FR120N mosfet module:
The original question was about a relay so PWM isn't relevant...
I doubt the regular Arduino (with the ATmega chip) is fast-enough to "challenge" any MOSFET, even if you max-out the PWM frequency. But if you are running it near its current limits a high switching frequency might push it over the edge.
I haven't had any issues with Arduino PWM speeds so far. I've only cooked two MOSFETs to date. The only real "cooking method" I’ve found is letting the supply voltage get too low. As the voltage drops, so does the gate drive level, and with the gate capacitance involved, there’s a point where low voltage and high switching speed combine; that’s when the magic smoke starts to appear.
No the switching voltage is much lower for DC. I went and looked at a couple of relays I have and they have a similar 250VAC/30VDC. I never worried about DC since I only went as high as 12V. The switchover arc is quenched by the zero crossing in AC but is dependent on the contact gap for DC.
I love this statement. Do you understand that a solenoid is an electric motor and will draw a very large current as the solenoid armature begins to move? Measure the solenoid coil resistance and use Ohm's law to compute the current at 72 volts.
Why do you want to control a solenoid with a relay? A relay is a switch operated by a solenoid, so switching a solenoid with a relay is using a solenoid to control a solenoid. Unless there's a good reason not to, I suggest controlling the solenoid directly with a MOSFET or DC SSR as others have suggested.
I disagree. The steady state current through a solenoid is limited by the DC resistance of the coil according to Ohm's law. The initial current is additionally limited by the EMF generated by the changing magnetic field as the current increases from zero to its steady state value.
A DC motor behaves differently because, once it is running, it behaves as a DC generator with the generator output voltage opposing the supply voltage, the difference between the two becoming the effective supply voltage and the current being that voltage divided by the motor's DC resistance.
If you think I'm wrong I'm happy to learn something new.
You know what this is probably the dumbest decision I made in my life, Don't respond to me, please. How do we all responses I am not a professional and anything of what I said should no longer be treated seriously, Aside from this I guess. In other words, I'm leaving.
The OP want the solenoid to move the armature, hold the armature and then release the armature all in 50 ms. Therefore the resistance must be quite low so the magnetic field can accelerate the armature and move it to it's seat and release it to return to the initial location all in 50ms. The coil must be low resistance to allow this to happen and this would cause an initial high current, a reduced current as the armature moves and produces back EMF, and finally high current when the armature is seated.
There is no requirement for repetition, as I read the spec, so heating is not a problem. If there is a rep rate, then the solenoid has to be designed to handle the heating.
