Energy monitoring on a tight budget: which measuring points should we connect first?

[SystemPulse]

I'm responsible for maintenance and energy at a mid-size plant. We have one transformer substation, a backup generator, a compensation panel and about a dozen distribution panels feeding the production halls, compressors and offices. Some panels already have energy analyzers, most don't.
Management approved a first phase for energy monitoring, but not enough to put an analyzer in every panel. Where should we start so the first phase is actually useful, and how do we avoid having to redo things when we expand?

[Technical Support]

Good question to ask before buying hardware. A common mistake is spreading the first analyzers across "interesting" machines and ending up with numbers that don't add up to anything. Start from the top of the single-line diagram and work down.
Phase 1: the backbone
1. Transformer / main incomer. This is the total plant load and the number closest to your electricity bill. Every other measurement is compared against it.
2. Compensation panel. Power factor and reactive power problems are usually visible here first, and they show up on the bill as reactive energy charges.
3. Generator. Lets you see when it starts and how much load it carries.
4. The largest consumers. Typically compressors, chillers or the biggest production hall. A few large loads often account for most of the consumption.
Phase 2 and later
Add the remaining distribution panels, then individual lines or machine groups where you need cost per department or per product.
Avoid rework later
- Name measuring points by location, not by device. For example "MDP-Compressors" rather than the analyzer's serial number. When an analyzer is replaced, the history still makes sense.
- Document CT ratios and wiring for every analyzer as you install it. Wrong CT ratios are the most common reason for wrong readings.
- Plan the communication path for the whole plant now, even if you only connect four analyzers: where the network switches are, which panels need a serial-to-Ethernet gateway, and which analyzers share a serial line.
- Keep the single-line diagram up to date. It is the map everyone will use to read the data.
Check your total
Once the main incomer and the sub-panels are measured, the sum of the sub-panels should be close to the incomer. A large gap points to an unmeasured consumer or a measurement error, and both are worth finding.
For reference, in a GreenSoft project at Forschner Turkey, 17 analyzers covering the transformer, generator, compensation and distribution panels were brought onto one screen with a single-line diagram: https://greensoft.ai/news/greensoft-...-line-diagram/
If you share your single-line diagram and analyzer list with us at https://greensoft.ai/get-in-touch/, we can help you plan the phases.