This manual serves as a standard for energy system designers and designers using M-Bus technology. The aim of this standard is to enable clear and transparent allocation of energy consumption to technological units (heating, cooling, ventilation, production, lighting, etc.) or to economic units (tenant, economic center, etc.). Furthermore, the aim of this standard is to prepare the entire measurement system for automatic data collection from individual meters, possible identification of potential energy savings and billing automation. This document has been developed and is progressively evolving based on our many years of experience in operating measurement systems in conjunction with Enectiva.
The main goals of our standard:
- Helping designers to design an energy measurement system
- Create only effective and efficient measurement systems
- Easy to connect to online energy management
It is always necessary to measure:
- Main power supply
- Main water supply
- Main heat or gas supply
Measure Technology Consumption Secondary:
- Electricity consumption at VZTS
- Consumption of electricity for cooling
- Water consumption for hot water in case of central heating
- Consumption of heat for hot water in case of central heating
- Consumption of electricity for indoor lighting
- Consumption of electricity for outdoor lighting
Secondary measures all energy for individual tenants or planned rental sections (water, electricity, gas)
If the tenant is not known during the realization and the space will be kept unoccupied, the preparation for the possibility of measuring will be carried out in the future. If more units are currently combined into one unit, but in the future they may be split among several tenants, the measuring points will be fitted with a spacer that can be easily exchanged for the meter.
Secondary measurement of economic centers
In the case of a measurement design for a comprehensive enterprise, it is necessary to take into account the secondary measurement of electricity of the individual economic centers. The basic division is the secondary measurement of administrative and production parts. Another subtle secondary measurement is welcome and depends on the type of operation in the enterprise.
Secondary measurement according to the size of appliances
Based on Pareto’s rule, 20% of appliances generate 80% of total consumption. It is the largest appliances that need to be measured on a secondary basis. In industry, these are mostly compressors, furnaces, presses, gastronomy shops, paint shops, integrated production and robotic lines. At the beginning of the measurement design it is crucial to know the largest appliances and then capture them by secondary measurement.
Meter requirements
The meters used for all types of energy must be equipped with an M-Bus interface with a communication speed of 2400 Bd / s. It is an open and globally used technology that has been designed to automatically capture data from meters. It is easy to install, reliable and easy to expand.
In cases where meters are placed outside the building, where it is not possible to bring the communication cable from the building, a meter with a pulse output for wireless data transmission is an acceptable solution.
M-Bus cabling requirements
The individual meters will be interconnected by a bus, which will be implemented with a J-Y (St) Y 1x2x0.8 mm2 cable or 2x2x0.8 mm2 cable, where it makes sense to use two pairs. The bus wires will be routed to the measurement and control distribution box (MaR), or to another easily accessible location where the 230V power supply is available. Each lead will be equipped with a label describing which part of the bus it is.
A 6A (B) circuit breaker with a short-circuit resistance of 10 kA will be left in the MaR switchboard for the purpose of connecting a central M-bus master and a space for 16 modules on a DIN rail.
An Ethernet cable with the possibility of using the building’s technical network for remote supervision will be brought into the MaR switchboard.
In the event that the MaR switchboard with the M-Bus central point cannot be equipped with an Ethernet connection to the technical network, a location will be selected for the central location where a sufficiently high quality mobile network signal is provided and accessible for service.
M-Bus topology
Possible bus topologies are star and tree. Circular topology is not allowed.
No terminators are required on the bus. And its maximum allowed length is 350m.
Connecting cables
The connection of the cables will be realized by using WAGO terminals located in the installation boxes with the visible “M-BUS” marking.
Bus cable routing
M-Bus cables will be routed away from power lines to avoid communication interference. In situations where concurrency cannot be avoided, the length of parallel guidance must be reduced to the minimum necessary.
If you want to implement a measurement project or help with its design, do not hesitate to contact us at project@enectiva.cz