Transformer Setup - GE 845 Instruction Manual

CHAPTER 4: SETPOINTS

Transformer Setup

General Setup
FASTPATH:
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Most of the setpoints from the transformer general setup are used for computation of the
hottest-spot winding temperature, aging factor, and accumulated loss of life.
Path:
Setpoints > System > Transformer > Transformer Setup > see "General Setup"
..\Transformer\General Setup
Item Name
Phase Compensation
Load Loss at Rated Load
Rated Wndg Temp Rise
No Load loss
Type of Cooling
Top Oil Rise over Ambient
Xfmr Thermal Capacity
Wndg Thermal Time Constant
Energization Winding Source
Year of Manufacture
Setup
Refer to the following explanations for setpoints, to select the correct values.
PHASE COMPENSATION
Range: Internal (software), External (with CTs)
Default: Internal (software)
Select the type of phase compensation to be performed by the relay. If set to Internal
(software), the transformer magnitude and phase shift compensations are performed
internally by the relay algorithm. If set to External (with CTs), the transformer phase shift
is externally compensated by the CT connections. The relay still performs magnitude
compensation when "External (with CTs)" option is selected.
When the phase compensation type External (with CTs) is selected, the relay does not
apply phase compensation internally as per the entered winding angles from the
transformer type selection. In this mode, the relay expects to measure already phase
compensated currents on its terminals. In this mode, the relay only performs magnitude
compensation.
LOAD LOSS AT RATED LOAD
Range: 0.001 to 20000.000 kW in steps of 0.001 kW
Default: 100.000 kW
This setting is taken from the transformer nameplate. If it is not available from the
nameplate, the setting value can be computed as P
rated current and R is the three-phase series resistance. The setting is used as input for
the calculation of the hottest-spot winding temperature.
RATED WNDG TEMP RISE
° °
Range: 55 C (oil), 65 C (oil), 80
°
Default: 65 C (oil)
This setting defines the winding temperature rise over 30°C ambient temperature. The
setting is automatically selected for the transformer type as shown in the following
figure. The data reflects the data outlined in ANSI/IEEE 57.91, ANSI/IEEE 57.92, and ANSI/
IEEE 57.94 standards.
Value
Internal (software)
100.000
65°C (oil)
10.000
OA
35
1.00
2.00
CT Bank 1 -J1
1950
=I
R n(W)
° ° °
C (dry), 115 C (dry), 150 C (dry)
SYSTEM
Unit
kW
kW
°C
kWh/°C
min
2
*R, where I is the winding
n(W)
4–75