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Tree Tech Model SPS
The Synchronous Paralleling Supervisor (SPS) consists of a
microprocessor based electronic device capable of monitoring and
modifying, through the load tap changer (LTC), the positions of
power transformer taps. Both individually and simultaneous tap
changes through interconnected SPS's is possible via serial data
ports included on each SPS controller.
The SPS performs the paralleling of up to 6
three-phase transformers or 18 single phase transformers through the
master-slave method. An individual three phase transformer or single
phase bank must be selected as the master, while all other are set
as slaves. This technique assures every tap change to be made by the
master transformer is simultaneously made by the |
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slave(s), keeping the same tap
in all transformers and avoiding current circulation between
parallel windings. In case of discrepancies in a tap between the
parallel transformers, the LTC operation is blocked. The LTC is
blocked if an occurrence of any other abnormal condition appears
such as a failure in communication or programming. |
The SPS incorporates the functions of several equipment
gears that were used in past times for controlling the transformers
parallelism, such as selector switches Master/Follower/Individual,
Manual/Automatic and Local/Remote, Tap Position Indicators, auxiliary
relays for electromechanical logic, among others. For this reason, the
command wiring and the number of components are greatly reduced, raising
substantially the overall system reliability while reducing the
installation and maintenance effort.
Integrated serial communications
using Modbus® RTU protocol makes it easy to incorporate the SPS with
other Tree Tech devices and/or third party products to create a
comprehensive monitoring and control solution. For example, the SPS module
can be linked to the Tree Tech AVR module to
create an Automatic Voltage Control system.
Like all Tree Tech devices, the SPS is designed and
thoroughly tested for operating in the most unfavorable conditions found
in electric substations, including surges, impulses, electromagnetic
interference and extreme temperatures.
Key Features
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Intelligent Tap Position
Measurement:
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Automatic
compensation of the interconnection cable resistance between
potentiometric position transmitter and SPS, allowing longer
distances with smaller cables (up to 600 meters with 1.5mm˛
conductors and 1000 meters with 2.5mm˛ conductors)
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Detection and
alarming of bad electrical contact in the potentiometric position
transmitter or in the interconnection cables.
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Indication of the LTC's
position and the type of tap position is user-selectable:
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simple numeric (e.g.
1...33),
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bilateral numeric
(e.g. -8...0...+8) or
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alphanumeric (e.g.
8L...N...8R)
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Number of positions set
between 2 and 50.
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Programmable resistance
values meets all types of LTC.
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Master/Slave/Individual
selection made directly on the front panel or through external dry
contacts.
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Manual/Automatic
operation mode selection made directly on the front panel or through
external dry contacts.
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Manual Raise/Lower
commands made directly on the front panel or through external dry
contacts.
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Current loop output
enables the remote indication and/or monitoring of the LTC's position.
Output range selectable by user at front panel (e.g. 0-1mA, 4-20mA)
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Four output relays (3
programmable) to indicate status and/or alarms.
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Type of transformer is
user-selectable: bank of single-phase transformers or three-phase
transformers
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Simultaneous start of
tap-change operation in all the transformers in parallel
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A unit can be withdrawn
from paralleling while keeping all other units in parallel by setting
it to individual.
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All parameters can be
configured through the SPS front panel or through the RS-485
communication port. All selections and commands can be performed also
through the RS-485 data link as well.
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