Relay Element Settings 2-5
SEL-300G Instruction Manual Date Code 20020206
Setting Descriptions
Enable System Backup Protection (N, D, V, C) EBUP = C
Set EBUP = C to enable the 51C voltage-controlled phase inverse-time overcurrent
element. Set EBUP = V to enable the 51V voltage-restrained inverse-time overcurrent
element. When EBUP = D or N, the elements listed above are disabled and the
following settings do not need to be entered. (See Phase Mho Distance Element for the
EBUP = D setting description.)
When EBUP = C:
Voltage-Controlled Time-O/C Pickup
(OFF, 0.5–16.0 A {5 A Model}; OFF, 0.1–3.2 A {1 A Model}) 51CP = 3.0
Voltage-Controlled Time-O/C Curve (U1–U5, C1–C5) 51CC = U2
Voltage-Controlled Time-O/C Time-Dial (0.50–15.00, U curves) 51CTD = 3.20
(0.05–1.00, C curves)
Voltage-Controlled Time-O/C EM Reset (Y, N) 51CRS = Y
51C Torque-Control Setting (SEL
OGIC Control Equation) 51CTC = 27PP*!60LOP
When EBUP = V:
Voltage-Restrained Time-O/C Pickup
(OFF, 2.0–16.0 A {5 A Model}; OFF, 0.4–3.2 A {1 A Model}) 51VP = 8.0
Voltage-Restrained Time-O/C Curve (U1–U5, C1–C5) 51VC = U2
Voltage-Restrained Time-O/C Time-Dial (0.50–15.00, U curves) 51VTD = 3.00
(0.05–1.00, C curves)
Voltage-Restrained Time-O/C EM Reset (Y, N) 51VRS = Y
51V Torque-Control Setting (SEL
OGIC Control Equation) 51VTC = !60LOP
For system backup protection, the SEL-300G Relay provides a choice of voltage-
controlled or voltage-restrained phase inverse-time overcurrent elements or phase
distance elements (discussed earlier in this section). The overcurrent elements include
a settable pickup, curve shape, and time-dial. Ten curve shapes are available. Curves
U1–U5 emulate the popular North American induction disk relays. Curves C1–C5
emulate popular European analog time-overcurrent relays. Operating characteristics of
the available curves are shown in Figure 2.27 to Figure 2.36.
When you set 51nRS = Y to enable electromechanical reset emulation, the relay
provides a slow reset that is dependent on the amount of current measured, similar to
an induction disk relay reset. When you select N, the relay fully resets the time-
overcurrent element one cycle after current drops below the pickup setting, similar to
analog and many microprocessor-based time-overcurrent relays. Select Y or N to
match the operating characteristic of other time-overcurrent protection protecting the
system near this generator.
Each of the elements is also equipped with a torque-control setting. When the equation
result is logical 1, the element is permitted to operate. When the result is logical 0, the
element is not permitted to operate. Use other protection elements, logic conditions, or
control inputs to supervise these elements if desired.
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