Wattics energy management solution for retail stores
Step-by-step procedures for monitoring and benchmarking of HVAC, lighting and power outlets within/across stores.
At this stage you have gathered information about the store’s electrical setup, and whether you can use the store’s Internet to transmit the readings to the online dashboard, see Stage 1 – Gathering information for your project proposal (in Retail Stores).
This second posts shows you how to use those insights to understand how you can measure the energy used by HVAC, lighting and power circuits, and how to translate this into the project proposal.
1 – Gathering information for your project proposal (in Retail Stores)
2 – Preparing your project proposal
3 – Preparing your quote
4 – Preparing your installation
5 – How to install your metering equipment
Step 1: Search for the master sheet
Your electrical diagram will likely have many sheets, and you must look for the sheet showing where the store gets its power from (Landlord Board or Power Company connection), this is your starting point.
In this example, you can see a sheet showing connections with the Landlord meter room and the Landlord MCCB distribution board. This is the sheet you are interested in.
Step 2: Identify the type of electrical system
You will generally get information on the type of electrical system used within the store looking at electrical connections on the electrical diagram. This is very important, because it can vary from store to store even in the same country (Wye or Delta). In this example, the sheet shows 4PN, meaning a 4-wire 3-phase + neutral line Wye system.
Step 3: Note the circuits specifications
Finding breaker size information will allow you to specify CTs with the correct primary AMP ratings (e.g. 300A CT for a circuit with a 300A MCB). The size of the cables is also generally indicated, e.g. 95mm2, which will allow you to specify CTs with the correct window size (hole diameter in mm2, inches or centimeters).
Step 4: Identify existing metering infrastructure
Diagrams often show Utility meters or meters deployed for previous sub-metering applications. Utility meters will typically be used for billing purposes and are a good indication of the circuits that must be monitored to compute the total energy use of the store. For instance the photo below shows that two Utility meters are deployed for the store, meaning that the total store energy consumption is the sum of both circuits.
Step 5: Locate the circuits you are interested in
Your goal is to find the circuits powering up HVAC, Lighting and Power outlets. For that, you must look at the distribution board(s) directly fed from the Landlord room or Power Company.
The screenshot below show DB-M1, which is directly fed from the Landlord room. DB-M1 feeds DB-1AC, DB-2AC, DB-1P and DB-2P through 100A 4PN and 75A 4PN circuits, respectively. This tells you that you can monitor the HVAC (AC) and power outlet (P) circuits with 4 sets of CTs, each set made of 3 x CTs (one for each phase). The same analysis of DB-M2 fed from the Landlord room too would show that the lighting (L) circuits of the store are powered through DB-1L and DB-2L via 75A 4PN circuits. This tells you can monitor the lighting circuits with another two sets of CTs. Other connections are spare (not used).
Step 6: Check the location of the boards
You must finally check the location of the boards and circuits you plan on monitoring. This is generally indicated on the wiring sheet. Knowing this allows you to decide if one meter can be used to monitor circuits on multiple boards, should the boards be in the same room, or if separate meters must be used for each board.
The project proposal
The project proposal becomes very easy once the electrical setup is clarified. You have identified which circuits must be monitored, their ratings and their location. The electrical installation used to illustrate this post would require the following metering equipment:
- 1 x 6-channel meter (4 circuits for DB-M1 + 2 circuits for DB-M2)
- 6 x 35mm2 100A CTs
- 12 x 25mm2 75A CTs
- Long CT cables to reach the two DB-M boards with one meter
The meters must be configured and wired for a 4-wire 3-phase Wye system.
That’s it, you’ve got your project proposal, and you can now move to
3 – Preparing your quote.
Please contact us at firstname.lastname@example.org if you need any clarification on the steps outlined.
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