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How and where to measure correctly?


Electricity meter lexicon - Lesson 1: Overview of meter types for energy management.

Here we would like to share our experience with a wide variety of metering systems. In this first lesson, we provide an overview and help with the selection of meter types in industrial plants.

Background: Energy meters are used to collect electrical quantities. Mostly, it is a question of recording the work performed or the (active) power drawn or "consumed". In individual cases, the measurement of other values can be important, e.g. to check the power quality. For example, some models measure the mains voltage, while more powerful meters also measure harmonics, total harmonic distortion, flicker and others. In practice, a distinction must be made between readable and non-readable meters, and between meter readings and instantaneous values.


Power Quality Meters / Power Quality Analyzers

Netzqualität-Messgeräte / Power Quality Analyzer (>800€)
  • Installation location: transformer underside in the NSHVT or for special consumers.
  • Data: Meter readings, powers, voltages, harmonics, THD, flicker, etc.
  • Communication interface: Modbus TCP
  • Examples: Siemens Sentron PAC 4200; Janitza UMG 508/512; Janitza UMG 96RM-E.

 

Our recommendation: Rarely necessary!

Normal multifunction meters

Zaehler celsa und Janitza
Normale Multifunktionsmessgeräte (250-500€)
  • Installation location: transformer bottom side in the NSHVT, outlets of equipment in the NSHVT.
  • Data: Meter readings, powers, voltages, sometimes harmonics, THD.
  • Communication interface: Modbus TCP
  • Examples: Siemens Sentron PAC 3200, Janitza UMG 96RM-EL, KBR multimess, Celsa TNM 96, Somec Diris A40; Econ Sense.

 

Our recommendation These meter types are our recommendation!

 

Simple meters

Simple meters (150-300€)
  • Installation location: outlets of systems in NSHVT, sub-distribution or control cabinet.
  • Data: Meter readings
  • Communication interface: M-Bus, partly proprietary
  • Examples: ABB, Finder, Berg, EMH, etc.

Our recommendation: Rarely cheaper!

Analog meters

Analog meters (~100€)
  • Installation location: transformers in the NSHV, large systems in the NSHV in older systems.
  • Communication interface: none
  • Data: None

Our recommendation: Please never!

The most important thing: choosing the right energy meter

Our experience and recommendations may help you in your decision. From our support in the creation of metering concepts, our installation activities and the good exchange with many customers of different trades, we can make the following recommendation:

Tip 1: Avoid analog electricity meters.

Tip 2: Choose multifunction meters with communication interface (e.g. Modbus TCP) if you want to be future-proof. Generally, these offer the cheapest and most comprehensive solution. All relevant data are recorded and instantaneous values can be read out. The systems are equipped with extensive interfaces and thus offer great compatibility with other data acquisition systems. Here you are on the safe side in 95% of the cases.

Tip 3: Power Quality Analyzers on the other hand are quite expensive and simply not necessary in most cases. They are only used where sensitive devices are connected that are allergic to flicker (short-term voltage fluctuations) or where harmonics of high harmonics have to be detected.

Tip 4: Make sure that the meter supports a standardized communication protocol and is not e.g. proprietary, i.e. not compatible with other manufacturers. Our recommendation goes to Modbus TCP, as this greatly facilitates the implementation of an energy management system.


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