Symbols and Glossary P54x/EN SG/La4
MiCOM P543, P544, P545 & P546
(SG) 14-5
SG
Symbols Explanation
PN> Wattmetric earth fault protection:
Calculated using residual voltage and current quantities.
PSB
Power swing blocking, to detect power swing/out of step functions (ANSI 78).
PSL Programmable scheme logic:
The part of the relay’s logic configuration that can be modified by the user, using the
graphical editor within MiCOM S1 software.
PUR
A permissive underreaching transfer trip scheme (alternative terminology: PUTT).
R
A resistance.
R Gnd. A distance zone resistive reach setting:
Used for ground (earth) faults.
R Ph
A distance zone resistive reach setting used for Phase-Phase faults.
RCA Abbreviation of “Relay Characteristic Angle”:
The center of the directional characteristic.
Rev.
Indicates an element responding to a flow in the “reverse” direction.
RMS The equivalent a.c. current:
Taking into account the fundamental, plus the equivalent heating effect of any
harmonics. Abbreviation of “root mean square”.
RP Abbreviation of “Rear Port”:
The communication ports on the rear of the relay.
Rx Abbreviation of “Receive”:
Typically used to indicate a communication receive line/pin.
S1 Used in IEC terminology to identify the secondary CT terminal polarity:
Replace by a dot when using ANSI standards.
S2 Used in IEC terminology to identify the secondary CT terminal polarity:
The non-dot terminal.
SIR
The source-to-line impedance ratio.
SOTF
Switch on to Fault protection. Modified protection on manual closure of the circuit
breaker.
SNTP
Simple Network Time Protocol
t
A time delay.
TCS
Trip circuit supervision.
TD The time dial multiplier setting:
Applied to inverse-time curves (ANSI/IEEE).
TE A standard for measuring the width of a relay case:
One inch = 5TE units.
TMS
The time multiplier setting applied to inverse-time curves (IEC).
TOC
Trip on Close (“line check”) protection. Offers SOTF and TOR functionality.
TOR
Trip on Reclose protection. Modified protection on autoreclosure of the circuit breaker.
Tx Abbreviation of “Transmit”:
Typically used to indicate a communication transmit line/pin.
UTC
Coordinated Universal Time
V
Voltage.
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