Monitor power consumption @ Breaker

[Gomeler]

Anyone doing this? I'm currently leasing a workshop and the landlord and I are trying to find a way to sub-meter my power. Considering how we're talking ~4 kW sustained with the goal of maxing out breaker(~6.5 kW), I'd like to accurately know my consumption so I'm not over/under paying.

I've run across the Acuvim CL which can monitor up to 3 lines -> http://www.powermeterstore.com/p8155/acuvim_cl.php

I've also run across a DIY approach that only monitors current. Thought about making a vac voltage monitoring circuit for it but I could end up overpaying if my PF is lower than 1 -> www.picobay.com/projects/2009/01/real-time-web-based-power-charting.html

There are lots of power meter options out there but lots of them only measure current via transducers and don't measure voltage or calculate power factor. Anyone out there have another solution?


Also, the ioBridge io-204 may be very interesting to some of you. I'm thinking about using one to remotely power cycle boxes via relays.

[MrTeal]

How about a Wattnode?
http://www.ccontrolsys.com/w/WattNode_Modbus

[Fefox]

Ive been using one of these for a few years, you can set it with your power cost and it does a running total for the day, week, month, its almost dead on with the power companies power meter.


http://www.currentcost.com/

[Gomeler]

Thanks for the suggestions guys, I'll check them out. I may have to reconsider on systems that solely use current transducers. I've been worried about the voltage droop causing the system to over count power consumption but maybe that isn't as serious of an issue as I'm thinking it is. Will make a decision this weekend and install it next weekend.

[DeathAndTaxes]

Thanks for the suggestions guys, I'll check them out. I may have to reconsider on systems that solely use current transducers. I've been worried about the voltage droop causing the system to over count power consumption but maybe that isn't as serious of an issue as I'm thinking it is. Will make a decision this weekend and install it next weekend.

They make meters which measure both current & voltage.  I will see if i can find a link.  I am assuming you are in US (NEMA wiring 240V split phase)?

Here is one system which is pretty comprehensive.
http://www.theenergydetective.com/

Here is a more bare bones (but could be connected to a PC for custom logging)
http://www.ekmmetering.com/ekm-metering-products/electric-meters-kwh-meters/basic-kwh-meter-100a-120-240-volt-3-wire-60hz-ekm-25ids.html

[MrTeal]

Thanks for the suggestions guys, I'll check them out. I may have to reconsider on systems that solely use current transducers. I've been worried about the voltage droop causing the system to over count power consumption but maybe that isn't as serious of an issue as I'm thinking it is. Will make a decision this weekend and install it next weekend.

Wouldn't you want to take into account voltage drop across the line if you're trying to estimate your rig's power use? Say your rig is drawing 10A on a 15A 120V cct with a 50ft run of 14gauge. You'll have about 2.3% Vdrop across the cable, so while your rig might be drawing 1172W (assuming PF1), you're actually drawing 1200W from that breaker and assuming no further upstream losses that's what your utility will be billing you for.

[Gomeler]

Thanks for the suggestions guys, I'll check them out. I may have to reconsider on systems that solely use current transducers. I've been worried about the voltage droop causing the system to over count power consumption but maybe that isn't as serious of an issue as I'm thinking it is. Will make a decision this weekend and install it next weekend.

They make meters which measure both current & voltage.  I will see if i can find a link.  I am assuming you are in US (NEMA wiring 240V split phase)?

Here is one system which is pretty comprehensive.
http://www.theenergydetective.com/

Here is a more bare bones (but could be connected to a PC for custom logging)
http://www.ekmmetering.com/ekm-metering-products/electric-meters-kwh-meters/basic-kwh-meter-100a-120-240-volt-3-wire-60hz-ekm-25ids.html

Yup, ran across those. The Acuvim I mentioned in the first post measures voltage and current at the breaker and does the job with a nice interface and an RS485 port. I was just fishing for more ideas to see if anyone used such things.

Thanks for the suggestions guys, I'll check them out. I may have to reconsider on systems that solely use current transducers. I've been worried about the voltage droop causing the system to over count power consumption but maybe that isn't as serious of an issue as I'm thinking it is. Will make a decision this weekend and install it next weekend.

Wouldn't you want to take into account voltage drop across the line if you're trying to estimate your rig's power use? Say your rig is drawing 10A on a 15A 120V cct with a 50ft run of 14gauge. You'll have about 2.3% Vdrop across the cable, so while your rig might be drawing 1172W (assuming PF1), you're actually drawing 1200W from that breaker and assuming no further upstream losses that's what your utility will be billing you for.

I'm measuring the entire building at the breaker, not at the outlet or at the PSU. Can't really factor in the line loses from the main breaker but that should be negligible.

[MrTeal]

Can you describe the setup in a little more detail then? Is there a main breaker box with a single 30A breaker that you're talking about monitoring, or does the workshop you're leasing have a subpanel?

[Gomeler]

Can you describe the setup in a little more detail then? Is there a main breaker box with a single 30A breaker that you're talking about monitoring, or does the workshop you're leasing have a subpanel?

Sub-panel. Breaker on input is 60amp @ 120v. There are then a number 15 and 20 amp breakers for circuits throughout the workshop. I will be measuring the curent and voltage on the two legs of the 240v line that powers the building. There is also another 30 amp 240v feed that I may or may not use to power more rigs.

[MrTeal]

Can you describe the setup in a little more detail then? Is there a main breaker box with a single 30A breaker that you're talking about monitoring, or does the workshop you're leasing have a subpanel?

Sub-panel. Breaker on input is 60amp @ 120v. There are then a number 15 and 20 amp breakers for circuits throughout the workshop. I will be measuring the curent and voltage on the two legs of the 240v line that powers the building. There is also another 30 amp 240v feed that I may or may not use to power more rigs.

If that's the case, I would bet that you could find an old analog electricity meter and just put it inline with your subpanel. They're getting removed by the boatload to be replaced with digital and smart metering, so there should be an abundant supply.

[Gomeler]

Can you describe the setup in a little more detail then? Is there a main breaker box with a single 30A breaker that you're talking about monitoring, or does the workshop you're leasing have a subpanel?

Sub-panel. Breaker on input is 60amp @ 120v. There are then a number 15 and 20 amp breakers for circuits throughout the workshop. I will be measuring the curent and voltage on the two legs of the 240v line that powers the building. There is also another 30 amp 240v feed that I may or may not use to power more rigs.

If that's the case, I would bet that you could find an old analog electricity meter and just put it inline with your subpanel. They're getting removed by the boatload to be replaced with digital and smart metering, so there should be an abundant supply.

Yup, looked in to that. Downside is I cannot read it via my computer and automate calculating the powerbill. Between the io-204 for remote powercycling, SSHing in to the boxes, and remotely monitoring the power consumption, I will hopefully only set foot on the site to install new gear and replace fans.