metering of individual loads....

[Fulthrotl]

i have a customer with a server room with a dedicated 5 ton AC, 3 phase 208 volts....

anyone have a metering system that they are fond of that works well, so
that the customer can be billed for the power they consume?


thanks...

 

[chris kennedy]

E-Mon D-Mon, love those things. Very easy for the end user to calculate the $$$.

 

[Fulthrotl]

E-Mon D-Mon, love those things. Very easy for the end user to calculate the $$$.

thanks... i've had other suggestions, all for emon dmon's.... well, that settles that....

customer has one already, and is getting nutty readings from it... saying a data closet
AC is drawing 12% of the total load of the entire building.

i've not played with one of these before... are there taps to select range? 'cause it's
almost an order of magnitude error in what common sense tells me the thing should
read, i haven't seen the bill yet, but someone is screaming 7,800 KWH for a month
for the AC in a 80 sq. ft. room with two server racks........

off to RTFM......

 

[ceb58]

thanks... i've had other suggestions, all for emon dmon's.... well, that settles that....

customer has one already, and is getting nutty readings from it... saying a data closet
AC is drawing 12% of the total load of the entire building.

i've not played with one of these before... are there taps to select range? 'cause it's
almost an order of magnitude error in what common sense tells me the thing should
read, i haven't seen the bill yet, but someone is screaming 7,800 KWH for a month
for the AC in a 80 sq. ft. room with two server racks........

off to RTFM......

Do not jump to the conclusion that something is wrong with the meter with out investigating. Our comm. buildings are around 120-150 Sq FT. With 2 racks of radios, a DC inverter and a UPS. If the A/C goes out it will go from 72 to over 100 in about 30-45min in the winter time and a lot quicker in the summer.

 

[Fulthrotl]

Do not jump to the conclusion that something is wrong with the meter with out investigating. Our comm. buildings are around 120-150 Sq FT. With 2 racks of radios, a DC inverter and a UPS. If the A/C goes out it will go from 72 to over 100 in about 30-45min in the winter time and a lot quicker in the summer.

understand.... but that 12% of the total building electrical is a 3 story office building, with a 50 ton a/c
on each floor.... it's 12% of the total building energy bill, for the ac in a server room? i'll be surprised
if that comes to pass... it'll be interesting to go troubleshoot this, and i can do it without the work van,
so i think some research is warranted... ;-)

 

[Rampage_Rick]

One would think the A/C in the server room would run almost 100% of the time if it was properly sized to the heat ouput of the servers.

On the other hand, office A/C runs what, 10% of the time during fair weather?

Keep in mind that power densities in server rooms have grown from 2 kW per rack to 12 kW per rack with some of the newest blade servers. The majority of that energy becomes heat. 12 kW = 3.5 tons refridgeration, so 10 racks of blade servers need 35 tons running 24x7.

Could it be possible that the meter is registering the entire server room load?

7800 kWh per month = 10.8 kW constant load
assuming 0.9 PF, that's about 12 kVA
at 3ph 208, that's about 33 amps per leg.

According to this thread a 5 ton A/C should draw about 7.5 kW. You've got 3.3 kW going somewhere else...

 

[kwired]

Does this server room ever draw in fresh air if the outdoor temp is lower? If not the required A/C load for that room probably does not vary much at all as the heat from the equipment is relatively constant. Other areas only need AC when conditions call for A/C. The A/C load in other areas probably is reduced after business hours but the server room remains fairly constant.

 

[hurk27]

Just one point to make is you might want to check with you state utility commission on what types of metering is allowed to be used for billing someone for money, I do a few campgrounds and apartment buildings that the property is primary metered and have install sub metering for the units, in all cases before they can start charging someone for electric usage they had to get the metering certified by the states weights and measurements to make sure it bills for the correct amount, or it can comeback and bite them. Just something you might want to pass along to the customer if it applies in your area? while I do some E-mon installs they are not acceptable until the install is tested.

we had one campground that had the mechanical meters double fed through them which would cause them to rack up twice the amount of KWH's, they were for 120 volt pedestals so they ran the hot to the left line side then the load went to the line on the second leg (right side) then to the pedestal breakers to the load, the state caught it and shut down the park for this and many other violations that the owners couldn't afford to do all the repairs, we gave them an estimate for over $220,000.00 just for the electric upgrades it needed, but the sewer system was over a million to bring it up to EPA's requirements, all it took was one complaint from a camper who knew how much his camper used and called the state in.

 

[kwired]

Just one point to make is you might want to check with you state utility commission on what types of metering is allowed to be used for billing someone for money, I do a few campgrounds and apartment buildings that the property is primary metered and have install sub metering for the units, in all cases before they can start charging someone for electric usage they had to get the metering certified by the states weights and measurements to make sure it bills for the correct amount, or it can comeback and bite them. Just something you might want to pass along to the customer if it applies in your area? while I do some E-mon installs they are not acceptable until the install is tested.

And some places you do not sell electrical energy at all unless you are a recognized power utility. The tax authorities will want sales taxes or whatever other fees apply. Usually not worth while to try to deal with all that vs either having separate meters from the utility company or some other arrangement where utilities are included with rent or lease payments - but definately can not be itemized by a per kWhr basis.

 

[hurk27]

And some places you do not sell electrical energy at all unless you are a recognized power utility. The tax authorities will want sales taxes or whatever other fees apply. Usually not worth while to try to deal with all that vs either having separate meters from the utility company or some other arrangement where utilities are included with rent or lease payments - but definitely can not be itemized by a per kWhr basis.

So very true, while here (Indiana) they allow sub metering, as long as it has been tested by the state and they follow the laws here that they are required to abide by.

We have many older large homes in towns all around here that many have sub metering installed when they were turned into apartments, and in some cases where they took large old retirement homes and turned it into apartments, even old motels/hotels but the most common is camp grounds and or trailer parks.

 

[cadpoint]

Cycle both sides of the machine, I've read here before where the heat is running the same time when one is not suppose to...:ashamed: