8. Electric Panel Design
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Figure 8-5. Example of Heat Movement – Open Installation
Electrical Design
General Information
Remote terminal units are manufactured in view of global standards that establish acceptable levels
of environmental and noise conditions normally found in control applications of generation,
transmission and distribution systems of electric energy, such as hydroelectric power plants (HPPs),
and power substations.
It is essential that the installation of these products follow rules of convenient project, established by
installation standards. Problems caused by electromagnetic interference (EMI), such as
communication and program execution failures, noise in analog variables and even loss of program,
can be caused by bad electrical design or installation.
The electrical design of the Altus RTUs must comply with the IEEE 518/1977, "Guide for
Installation of Electrical Equipment to Minimize Electrical Noise Inputs to Controllers External
Sources". The most important points are covered next.
Cabinet Power
The power supply of the control system must include main circuit breaker. We recommend the use of
terminals for general power supply of mounting panel with integrated fuses, as well as the use of an
outlet providing 127 or 220 Vac, for the programming terminal. The outlet must include ground pin
to allow proper grounding of programming terminal. All the outlets of the cabinets must have clear
indication of its voltages.
Distribution of Cables in the Cabinet
The correct distribution of cables in the cabinet and the correct grounding of the equipment ensure
electromagnetic compatibility (EMC) of the installation.
It is important the proper distribution of the electric panel power supply, via distribution bars or
connecting terminals.
From these general distribution points, a specific cable is used to each supply point. Local branches
should be avoided in modules supplies, thus decreasing the cables pathways leading high-current.