Hello everyone, first post here, i'm planning to revamp my home automation arduinos where i had used nanos and megas with nrf24l01s but now updating everything to esp 32s with mesh networking, i was using normal mechanical 10a to switch 2000W and 1500W 220v space heaters before even used a couple of SSRs before so i'm switching everything to SSRs but i've just found out that i was supposed to be using heat radiators on the SSR's usually if using them above 5~10a depending on the brand, is this really necessary knowing that i'm planning to buy 25A ones just to be sure and the biggest heater i'm using right now only pulls about 7A max usually less, the small one which is 750W is only pulling 3A measured with a clamp, do you think i can safely pull it off for long term use ? and where can i buy genuine good quality ones without breaking the bank ?
i can't know for sure if the ones on aliexpress are genuine since i've seen a guy take them apart and find a 12A triac instead of a 25A one... any advice would be greatly appreciated, thanks !!
All the amp ratings are based on how fast the internal die can dissipate the heat when switched on, and that relates to the on/off time when in use.
All the SSRs that I have purchased on Ebay have had an aluminum plate that must be mounted to some type of metal to aid in heat dissipation and they do get warm, but not hot!
I also have some SSRs removed from a convection soldering oven that are high current, with no heat sinking and they worked for more than 20 years. They have similar ratings as the Ebay units.
Paul
Interesting approach. I assume you will be driving the SSRs with at least there minimum voltage requirement at the terminals. The best approach is to look at the appliance name plate, then divide the wattage by the voltage. If your voltage is lower use that number. You can validate this with a clamp meter. This will give you the amps you need to switch. With lamps it is a different story, Typically Inrush current for an incandescent lamp is about 15x (depends on configuration and temperature) the steady-state current. Duration of the inrush current of incandescent lamps decays in about 100 milliseconds. With this be sure the SSR will safely work with the lamp. You can also use LED Light bulbs but check this first: https://adlt.com.au/led-driver-inrush-currents/ purchase reputable brands you should be OK. Triac's have a voltage drop is between 1.5V and 2V. Use the 2V to calculate the amount of heat that will be generated. For example 1 amp * 2V = 2 watts of heat to get rid of. Most of the time when I use the SSRs I put them in a metal junction box, I have had them operating for over 20 years. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
Thanks for your info. It is really helpful for me.
supermining:
Thanks for your info. It is really helpful for me.
You are welcome.