Operation Cost ?

[HamidEle]

Have anybody here estimated operation costs for electrical equipment? I was asked by the client to assess the operational costs for electrical cost for their project. I haven't done this before. Anyone can shed some light on it. Appreciate it first here.

 

[waross]

It depends to some extent on the reason for the request.
I had a similar request from a manager who wanted to divide the power charges amongst the various departments. I went through the one-line diagrams and totaled up the horse power and other major loads for each department. The power bill was then divided between the departments based on the ratio of installed HP and equipment.
I explained to the manager that given the diverse load factors of our various motors, this method was not very precise but I could give an answer in a few hours. A precise survey may require several thousands of dollars worth of test equipment and one or more months of measurements.
The manager was happy to accept the quick estimate, imprecise as it may be.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[HamidEle]

We are trying to decide which equipment shall be used are still at the early stage of the project.

 

[MiketheEngineer]

Figure kilowatts required and call your local power company >??

 

[mesutphen]

Determining electrical operating costs can be very simple or very complex, depending on the equipment. Obviously, you will need to determine the power cost associated with operating the equipment. You probably also want to consider the maintenance costs associated with maintaining the equipment in an operating status, both in manpower to do the maintenance and supplies.

The power cost can be the complex part. If you have a relatively-small, purely resistive load (i.e. heaters), take the kilowatts and the time operating and multiply by your power cost. If you have a large load and/or load with capacitance or inductance (i.e. pretty much everything besides heaters) you have to consider more.

First, is your total load going to cause your power rate to change? Power companies typically charge by how much power you use during a billing cycle. If you use up to 1000 kilowatt-hours (KW-hr), you get charged one rate whereas if you use 1000-2000 KW-hr, you get charged a different rate (typically a lower rate for higher usage). You should also take into account if this power is going to be used during peak power periods, since the power company may charge you more for using power during these periods.

Second, what will be the effect on your reactive power? If you add inductance or capacitance (typically motors), this will change your reactive power. Power companies do not want you to use a lot of reactive power, and many times will charge a fee if you exceed a certain amount. Your equipment should tell you the power factor that it will run at. This will allow you to determine the reactive power it will consume. If it turns out you will exceed the power company's limit on reactive power, you have two things you can do:
1. Pay the fee. This would be a monthly cost with no capital cost involved.
2. Add compensation to offset the reactive power. If you have mainly inductive loads (motors), you can add capacitors to offset this. If you have capacitive loads, you can add inductors (reactors) to offset this. This will add to the capital cost, but will negate the monthly fee.

Third, can your current electrical system handle the added load? Obviously, if it cannot handle the additional load, you will have to look into upgrading your electrical system. Although, since your client is asking you to assess their project, they have probably already made sure of this.

There are probably more things to consider that I am forgetting right now, but these three will get you a very accurate estimate of what your operating costs will be. If you want a simple way to estimate operating costs, simply take the KW loading of the new equipment and multiply it by your power cost and hours it will operate.

 

[tygerdawg]

I'd suggest for precise-as-possible cost figures, get your power provider involved (in addition to previous excellent suggestions). I know of one facility that wanted to reduce their power costs. Ultimately, they discovered their rates they were being charged were based on peak power usage. When they tried to adjust their equipment startup schedule & other power usage to reduce the peak demand, it seems the power provider started playing a game of "rate manipulation voodoo" in order to maintain their revenue stream. Well...at least it seemed that way. The rates charged were set to a very complex formula. The monthly charges were only minimally reduced.

Years ago I started shifting my home from electrical heat to gas heat (furnace, hot water, & stove). My electric bills starting dropping due to reduced consumption. It seemed my rates increased...due to reduced consumption. Hmmm...

TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering

http://www.bluetechnik.com