How power works in a data center: What you need to know | 220v Contactor Relay

“OK, you hold that small bulb across that plug, I’ll connect this 9v battery across the live & neutral pins…”

Yes, I get that there are societal differences between Eastern ideals and Western ideals. Please understand that Americans also build cheap crap, too- but being across an ocean makes buying and selling a little different, especially with a language barrier and different societal norms. I’ve been bitten by a couple of misrepresented products before on AliExpress, (RGB mechanical switches that were actually just RGB LED’s), but that was my fault- I didn’t look very carefully, and didn’t do my due diligence.

Reading the related article will help you to not jump with such conclusions. It is stated very clear, to BE USED WITH FUSE!. Is no fuse on the board because the FUSEs module is separate from the command board. Just some common sense modular desing.

I use these kinds of SSRS in high current applications driving kilns. we protect ourselves quite happily by having a contactor in the line. The SSR when it fails fails ON and the contactor is help closed all the time but overtemp or any other kind of alarm will release teh contactor and break teh circuit. My recommendation – and no one wil ever get to the bottom of the comments on this feed – is to add a contactor in series which is help closed and opened in an alarm condition. Then the SSR can fail to its heart’s content and you’re good. The SSR is of course much better at switching on and off than the relay which will fail eventually from on/off transients. As usual – YMMV

(So your distribution wire can be thinner, and so cheaper, mainly because you have less current, but also because you can have a slightly higher voltage drop with less consequence !)

Most people posting seem to have three stories, I only have two. Hard to believe I learn faster than you all; I must have just forgotten the other times.

A mains isolation transformer. wdwd [GFDL], via Wikimedia CommonsAn isolation transformer isolates the mains supply from the earthing system. This does not change any of the risks inherent to the mains voltage or other high voltages in your device, but it does provide you with some level of protection should you accidentally provide a path to earth from a live component.

The Mode dial on the left shoulder is used to select the camera’s operating mode. An angled panel allows you to view four buttons from either the rear or above: Menu, Movie, Exposure Compensation, and Auto-exposure Lock buttons.

You are correct and if you design this type of solution you already know this. With PCB design, the alternatives are heavier copper, wider traces, plating up copper in the areas that carry heavy current or a combo of any of the three. But you can only go so far with these solutions. Hack apart a known good SSR and I bet they use the exact same solution.

The Sony Alpha A33 lacks one feature found in the A55V (the only version of the A55 that’s sold in the US market) — a built-in GPS receiver. It’s still possible to geotag images and movies from the A33, but doing so will rely on an external GPS logging device and PC software that can backtrack to calculate the location at which images and movies were shot — not nearly as seamless a solution as the A55V’s ability to geotag images and movies straight out of the box.

One possibility (on contactors) is to have a split pole with a copper ring one one half. This is similar to a shaded pole motor. The current which is induced in the copper ring (shorted winding) is out of phase with the current in the main winding and smooths out the zero crossings. Another possibility, mostly used on valves, is to rely on the inertia of the core, here the dampening effect of the fluid also helps. The device is just not fast enough to follow the 100Hz (or 120Hz in some oversea countries) ripple.

One nice thing about the Sony A55 and A33′s electronic viewfinder is that the Fn menu is also available in the viewfinder display; you can make many camera settings without taking your eye from the viewfinder eyepiece. As I became more familiar with the camera’s controls, this led to a very efficient shooting style, although it would take more than the few days I’ve had with the camera thus far for this to become second nature.