2-6 Relay Element Settings
Date Code 20020206 SEL-300G Instruction Manual
RELAY CONFIGURATION SETTINGS
The SEL-300G Relay provides several settings that configure the relay for the particular
generator being protected. These settings appear in Group settings or in the Global settings.
Note: All relay settings are made in secondary quantities (amps, volts, ohms, or watts).
Group 1, Group 2 Configuration Setting Descriptions
Relay Identifier: (39 Characters)
RID = GENERATOR
Terminal Identifier: (59 Characters)
TID = TERMINAL
The Relay Identifier and Terminal Identifier settings are text settings that allow you to
identify this relay application. The text you enter in these settings appears at the top of
the serial port command responses sent from the relay. These identifiers assist you in
analyzing data collected from individual relays. Suggested identifier settings include
the name, number, or position of the generator protected and primary or backup
protection designation for the relay itself.
Phase (IA, IB, IC) CT Ratio (1–6000; 5 A models) CTR = 100
(1-30000; 1 A models)
Differential (IA87, IB87, IC87) CT Ratio (1–6000; 5 A models) CTRD = 100
(1-30000; 1 A models)
Neutral (IN) CT Ratio (1–10000) CTRN = 100
Phase (VA, VB, VC) PT Ratio (1–10000) PTR = 100
Neutral (VN) PT Ratio (1–10000) PTRN = 100
Synch-Voltage (VS) PT Ratio (1–10000) PTRS = 100
Protection instrument transformer ratio settings allow the relay to display meter and
event report quantities in primary amperes, kilovolts, megawatts, and megavars. Enter
these settings as a ratio to one. For instance, a 1000:5-phase current transformer ratio
yields CTR = 200.
Figure 2.3 illustrates selection of the CTRN and PTRN settings. When a neutral
current transformer is connected directly in the generator neutral circuit, set CTRN
equal to the current transformer ratio to one.
In applications where the neutral current transformer is connected in the grounding
transformer secondary circuit, set CTRN equal to current transformer ratio to one. The
relay will report the current in the grounding transformer secondary rather than the
generator primary neutral current.
In high-impedance grounded applications, the relay VN input can be directly connected
to the generator grounding transformer secondary if neutral voltages during ground
faults will not exceed 300 Vac. When directly connected, set PTRN equal to the
grounding transformer voltage ratio to one. If an auxiliary transformer is connected
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