Schweitzer Engineering Laboratories SEL-587Z - Breaker Auxiliary Contact-Current Transformer Saturation; Commissioning Testing

GL.3
Date Code 20020903 SEL-587Z Relay
Glossary
Breaker Auxiliary Contact—Current Transformer Saturation
Breaker Auxiliary Contact
An electrical contact associated with a circuit breaker that opens or closes to
indicate the breaker position. A form-a breaker auxiliary contact (ANSI
Standard Device Number 52A) closes when the breaker is closed and opens
when the breaker is open. A form-b breaker auxiliary contact (ANSI Standard
Device Number 52B) opens when the breaker is closed and closes when the
breaker is open.
Breaker-and-a-half
Configuration
A switching station arrangement of three circuit breakers per two circuits; the
two circuits share one of the circuit breakers.
CCVT
Coupling-capacitor voltage transformer that uses a capacitive voltage divider
to reduce transmission voltage to a level safe for metering and relaying
devices. See CVT.
Checksum
A method for checking the accuracy of data transmission involving
summation of a group of digits and comparison of this sum to a previously
calculated value.
CID
Checksum identification of the firmware.
Cold Start
Beginning a system from power up without carryover of previous system
activities.
Commissioning Testing
Testing that serves to validate all system ac and dc connections and confirm
that the relay, auxiliary equipment, and SCADA interface all function as
intended with your settings. Perform such testing when installing a new
protection system.
Communications Protocol
A language for communication between devices.
Contact Input
See Optoisolated Input.
Contact Output
Relay outputs that affect the state of other equipment. Connect contact outputs
to circuit breaker trip and close coils, breaker failure auxiliary relays,
communications-assisted tripping circuits, and SCADA systems.
Control Input
See Optoisolated Input.
Control Output
See Contact output.
Coordination Timer
A timer that delays an overreaching element so that a downstream device has
time to operate.
CT
Current transformer.
CT Subsidence Current
Subsidence current appears as a small exponentially decaying dc current with
a long time constant. This current results from the energy trapped in the CT
magnetizing branch after the circuit breaker opens to clear a fault or interrupt
load.
CTR
Current transformer ratio.
Current
Transformer Saturation
The point of maximum current input to a current transformer; any change of
input beyond the saturation point fails to produce any appreciable change in
output.