Step 1: Add Constants

First lets add calculation tags for the Base Rate and Service Charge. This way when they change (increase) you only have to change a single tag.

Next type in your name. I have organized my tags such that this is in a Calculations/Tariffs structure. This is using the Context tag type, something that helps with organizing tags.

Then go to the Calc tab. We are using a Constant for this tag.

To make sure that I don't mix up dollars and cents, I'm making everything in $. The reason I chose dollars is to make the Engineering Units look clean in the Display tab

Now do the same for the monthly base charge.

Step 2: Calculate kilowatt-hours

If you have a meter that you are reading KWH directly, and it is resetting for you, you can skip this step. To keep the number of tags to my SCADA as few as possible, I am only reading kW and am using a totalizer tag to calculate my kwh.

First I create a Totalizer Tag to calculate the kw-s.

I have the totalizer looking at the Power tag as the source.

This tag resets every month.

Step 3: Convert kWs to kWh

Then in another calculation tag I do my first expression for this example, and call it kW-HR. In this I select expression and the input box on the right.

This expression is very simple, I divide the [kw-S] tag (which is in the same "folder" as the kW-HR tag I'm creating) by 3600, the number of seconds in an hour.

When you select OK, the value will show up in the Calculation tag box. At this moment we have used 687 kWh this month.

Step 4: Putting it all together

Now for the last step, calculate the current cost of power this month.

For this we create our last calculation tag of the example:

I have placed this tag in the Monthly Power context and had to reference up a couple levels in the tag hierarchy to get to the right one, [Calculations\Tariffs\Standard] and [Calculations\Tariffs\Standard Base Charge].

The result of this equation, as of today, is: $120