Application; User-Defined Measuring Ranges - ABB REC 561 User Manual

ABB Network Partner AB
Version 1.0-00
October 1996
Function:

1 Application

2 User-defined measuring ranges

Direct current measuring unit
Optional
Fast, reliable supervision of different analogue quantities is of vital impor-
tance 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 pressure in circuit breakers
Different measuring methods are available for different quantities. Cur-
rent 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 measur-
ing 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 usu-
ally 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 differ-
ent measuring converters occurs within different control, protection, and
monitoring terminals and within the higher hierarchical systems in the
secondary power system.
The REC 561 control, protection and monitoring terminal have a built-in
option to measure and further process information about up to 36 different
direct current information from different measuring transducers. Six inde-
pendent measuring channels are located on each independent mA input
module. Each REC 561can accept up to six independent mA input mod-
ules.
Information about the measured quantities are then available to the user
on different locations:
• Locally by means of a built-in man-machine-interface (MMI)
• Locally by means of a front-connected personal computer (PC)
• Remotely over the LON bus to the station control system (SCS)
• Remotely over the SPA port to the station monitoring system (SMS)
The measuring range of different direct current measuring channels is set-
table by the user independent on each other within the range between -20
mA and +20 mA in steps of 0.01 mA. It is necessary only to select the
upper operating limit I_max higher than the lower one I_min.
1MRK 580 154-XEN
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