Da fu?  Air conditioner load - reactive. - Page 1
Forum section: electronics / beginners

author: paulca
author_rank: Super Contributor
timestamp: September 08, 2020, 06:46:45 pm
content: Normally I see a -100W+ (- actually) of reactive. But I turned my aircon on and this happened (attachment).I still don't understand what this meter is telling me.

author: paulca
author_rank: Super Contributor
timestamp: September 09, 2020, 10:19:06 am
content: My -100W reactive would suggest 100W worth of capacitance?The +380W reactive would suggest the air-con compressor has 480W (nearly 50%) inductive load?

author: Zero999
author_rank: Super Contributor
timestamp: September 09, 2020, 12:10:30 pm
content: Yes the negative sign means capacitive.To be pedantic reactive power doesn't exist and isn't measured in Watts. The correct term is apparant power, which is measured in VA.

author: mikerj
author_rank: Super Contributor
timestamp: September 09, 2020, 12:29:44 pm
content: If it's an older system with a simple induction motor than they can have pretty poor power factors.

author: paulca
author_rank: Super Contributor
timestamp: September 09, 2020, 12:35:24 pm
content: Quote from: Zero999 on September 09, 2020, 12:10:30 pmOr kvar. It's not really a concern to me anyway the "power" value is real power, as charged, so the reactive measurements are just a novelty.Still, I am left wondering how I have a constant 100W of capacity load. I'm also still baffled about the spike of about 140W for 20 minutes every hour. I went on holiday and shut everything down except 1 PC, the Wifi router and a few low power odds and ends. It was still there. I confirmed it's not the fridge or freezer by switching them off for an hour and it's still there.I can't think of anything else that would consume 140W periodically.The air con unit is about 3 years old, but it's probably a basic 1.5kW compressor and a few high flow fans.

author: madires
author_rank: Super Contributor
timestamp: September 09, 2020, 01:01:14 pm
content: Quote from: Zero999 on September 09, 2020, 12:10:30 pmP_apparent = sqrt(P_effective^2 + P_reactive^2)orP_apparent = P_effective + j P_reactive

author: drussell
author_rank: Super Contributor
timestamp: September 09, 2020, 01:31:17 pm
content: Quote from: paulca on September 09, 2020, 12:35:24 pm100 VA capacitive reactance isn't really that much, and you didn't even unplug that PC. Did you actuallyunplugall the other stuff in your house or use a physical shut-off switch (or open all the breakers)? The bridge rectifier -> capacitive-input filter in most devices will typically appear with a large capacitive reactive component, hence the requirement for modern higher power stuff to have PFC.I would try shutting everything down, then shut off all the breakers and see what happens.Unless you have some huge capacitor in some power filter somewhere, it should go towards 0 VAR(eactive) as things are actually isolated from the line.

author: paulca
author_rank: Super Contributor
timestamp: September 09, 2020, 03:50:52 pm
content: Unplugged or "switched off at the wall" as we say here.The catch with monitoring it with everything switched off, ... I need the sensor, wifi and PC switched on for it to monitor, which means the main plugs breaker in.

author: paulca
author_rank: Super Contributor
timestamp: September 09, 2020, 05:45:52 pm
content: It's great fun this. Spot the load.3D Printer. The initial two "blocks" are the bed, then the extruder heating. The spikes from then on are both clicking in and out.