Siemens SG8158-00 manual Glossary

Glossary

address Unique four-digit number representing the location of a specific function parameter stored in the ISGS relay.

address block Unique four-digit number ending in two zeros representing the location of a specific function stored in the ISGS relay.

average line voltage Arithmetic average of AB, BC, CA line-to-line voltage (3-wire and 4-wire modes) (VAB+VBC+VCA)/3 = VAVG.

average phase current Arithmetic average of phase A, B, and C currents. (IA+IB+IC)/3 = IAVG.

average phase voltage Arithmetic average of A, B, and C phase voltages (4-wire mode only). (VA+VB+VC)/3 = VAVG.

binary input Optically isolated voltage level sensor with a fixed threshold. The input is considered activated if voltage above the threshold is applied and de-activated if no voltage or voltage below the threshold is applied. The status of a binary input is monitored by the relay and state changes are recorded in the event log. Actions matrixed to a binary input can be set to be performed when the binary input is acti- vated (hi) or de-activated (lo).

binary output ANSI rated dry output contact that can be matrixed to a binary input of a protective function for closing.

Breaker Failure (50BF) Relay function that responds to a fault condition where any phase current being measured by a CT does not drop below a programmed level. Whenever another protective function activates the contact identified by the breaker parameter, this function will wait until the set amount of time has expired. Then it checks the phase cur- rents. If they are not equal to or less than the set pickup value, the function executes its defined actions.

Breaker Mechanism Relay function that can be enabled to sense a breaker mechanism error and cause an action to be taken and an event being logged if the a- and b-switches are ever both closed continuously for more than 100 ms. No other time delay is implemented. When this function detects the error, it is considered to be in pickup. It goes out of pickup when the condition is no longer present.

Caution Indicates a potentially hazardous situation which, if not avoided, could result in moderate or minor injury.

Comm Event Relay function that can be set to allow the remote activation of the breaker and binary outputs.

CT Configuration A function to set up the ISGS relay to match phase CT primary rating, neutral or ground CT primary rating, and the CT input's normal power flow settings of an electrical distribution system.

Current Balance Relay function that protects against an unbalance in the phase currents. The function monitors the phase currents for approximate balance (of equal magni- tude). Balance is defined as the ratio of minimum to maxi- mum current, where the maximum current is the largest and the minimum current the smallest of the three phase cur- rents. The current is considered balanced and will not cause

an alarm. The function monitors for balance when the maxi- mum current is larger than the current balance pickup value. An alarm occurs when the min/max ratio is smaller than the current balance factor.

current sensor Toroidal current transformer providing cur- rent level data and operating power for fault protection and metering. Its rated primary current establishes the maximum continuous current rating of the circuit breaker. Its rated sec- ondary current is 0.5 A at rated primary current. Sensors used in Static Trip III trip units are encapsulated in polymeric material to protect the windings and prevent motion during short circuit fault conditions.

Curve Parameter of several ISGS protective functions that allows the selection of a definite time delay or a characteristic curve.

custom curve A user-definable protective curve.
Danger Indicates an imminently hazardous situation which,
if not avoided, will result in death or serious injury.
Device Configuration A function to set up the ISGS relay
to match line frequency, phase sequence, and breaker con-
nection settings of an electrical distribution system.
Directional Neutral or Ground Time Overcurrent (67N)
Relay function that protects against neutral or ground time
overcurrent condition. This function uses a selected time
overcurrent characteristic curve to determine the trip time,
and the voltages present on the VTs to determine the current
direction. Tripping occurs when the neutral or ground current
exceeds the programmed pickup at 100% or drops below
the pickup at 95% for a period of time equal to the delay time
setting. The pickup must remain active for the entire delay
time for a trip to occur. If the overcurrent condition subsides
in less time than the delay time, the pickup will go inactive
and the directional neutral or ground overcurrent function will
reset. When tripping occurs, the actual condition that caused
the trip is recorded in the device's nonvolatile trip log.
Directional Phase Time Overcurrent (67)	Relay func-
tion that protects against a phase overcurrent condition. This
function uses a selected time overcurrent characteristic
curve to determine the trip time, and the voltages present on
the VTs to determine the current direction. Tripping occurs
when any one phase current exceeds the programmed
pickup at 100% or drops below the pickup at 95% for a
period of time equal to the delay time setting. The pickup
must remain active for the entire delay time for a trip to occur.
If the overcurrent condition subsides in less time than the
delay time, the pickup will go inactive and the directional
phase overcurrent function will reset. When tripping occurs,
the actual condition that caused the trip is recorded in the
device's nonvolatile trip log.
event log Chronological record of significant	events	that
occur during relay operation. Includes operation and		fault	G
events.

Filter Parameter of several ISGS protective functions that sets the sensing method—rms or fundamental—used by the function in its pickup calculations.

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