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Monitoring of DC analog measurements
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Fast, reliable supervision of different analog quantities is of vital importance during the
normal operation of a power system. Operators in the control centres can, for example:
•
Continuously follow active and reactive power flow in the network
•
Supervise the busbar voltages
•
Check the temperature of power transformers, shunt reactors
•
Monitor the gas pressure in circuit breakers
Different measuring methods are available for different quantities. Current and voltage
instrument transformers provide the basic information on measured phase currents and
voltages in different points within the power system. At the same time, currents and
voltages serve as the input measuring quantities to power and energy meters.
Different measuring transducers provide information on electrical and non-electrical
measuring quantities such as voltage, current, temperature, and pressure. In most cases,
the measuring transducers change the values of the measured quantities into the direct
current. The current value usually changes within the specified mA range in proportion
to the value of the measured quantity.
Further processing of the direct currents obtained on the outputs of different measuring
converters occurs within different control, protection, and monitoring terminals and
within the higher hierarchical systems in the secondary power system.
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The REx 5xx control, protection and monitoring terminal have a built-in option to mea-
sure and further process information from 6 up to 36 different direct current information
from different measuring transducers. Six independent measuring channels are located
on each independent mA input module and the REx 5xx terminals can accept from one
up to six independent mA input modules, depending on the case size. Refer to the tech-
nical data and ordering particulars for the particular terminal.
Information about the measured quantities is then available to the user on different lo-
cations:
•
Locally by means of the local human-machine-interface (HMI)
•
Locally by means of a front-connected personal computer (PC)
•
Remotely over the LON bus to the station control system (SCS)
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