EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: gr8BlueSmokeEscape on September 02, 2022, 03:55:02 pm
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I would like to switch AC and DC from a common bus for multiple digital outputs (user requirement, not my idea). The end use case is a digital out from a ucontroller controlling a relay that could switch either 120VAC 0.6A or 24VDC 3A through a normally open SSR from a common bus powered by a spring clamp connector entry on the PCB. My question is whether an SSR exists that could satisfy these requirements under $30. I found AQZ207G from Panasonic which is 200 VAC/VDC 2A, however that does not get me to the required 3A. For AC the typical configuration for an SSR is triac, thyristor, etc and for DC is IGBTs or mosfets as far as I can tell. Is there a specific SSR topology that can handle both AC and DC? Alternatively, if you can think of a different device or solution to this issue I would be very grateful![attach=1][attachimg=1]
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Is SSR a customer requirement?
A normal electrmechanical relay would do this with ease and costs a fraction of $30.
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It's my aim at getting close to their max switching frequency specification. I understand that there is no way they are ever going to utilize it at 100 Hz, nor can an SSR handle 100Hz smoothly, but I'm absolutely sure a mechanical relay would not be able to handle 100 Hz! I think most of the issue here is customers making requirements documents without having a proper sitdown beforehand. I just talked them into dropping the 3A requirement which would have been used to drive some solenoids in favor of external interposer relays, so I think I'll consider the issue solved. However, if you have any insight on SSR AC/DC architecture it would be much appreciated from a more intellectual frame of reference.
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Solenoids at 100 Hz?
Before you do any more work, you need face time with this customer.
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Using MOS-GATED power transistors in AC switch applications: https://www.irf.com/technical-info/designtp/dt94-5.pdf (https://www.irf.com/technical-info/designtp/dt94-5.pdf) :popcorn:
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Solenoids at 100 Hz?
Before you do any more work, you need face time with this customer.
It's possible to PWM a solenoid to use less energy to keep it in the activated state, which could be the application. It's also possible he's confused with the switching frequency and the highest possible AC frequency of the current being switched.
It's my aim at getting close to their max switching frequency specification. I understand that there is no way they are ever going to utilize it at 100 Hz, nor can an SSR handle 100Hz smoothly, but I'm absolutely sure a mechanical relay would not be able to handle 100 Hz! I think most of the issue here is customers making requirements documents without having a proper sitdown beforehand. I just talked them into dropping the 3A requirement which would have been used to drive some solenoids in favor of external interposer relays, so I think I'll consider the issue solved. However, if you have any insight on SSR AC/DC architecture it would be much appreciated from a more intellectual frame of reference.
The easiest way is an isolated DC:DC converter, a MOSFET driver and MOSFETs.