GE 845 User Manual

CHAPTER 4: SETPOINTS SYSTEM
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 4–75
Transformer Setup
General Setup
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”
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.
FAST PATH:
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
R
=I
n(W)
2
*R, where I
n(W)
is the winding
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 ° C (dry), 115 ° C (dry), 150 ° C (dry)
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.
..\Transformer\General Setup
Item Name Value Unit
Phase Compensation Internal (software)
Load Loss at Rated Load 100.000 kW
Rated Wndg Temp Rise 65°C (oil)
No Load loss 10.000 kW
Type of Cooling OA
Top Oil Rise over Ambient 35
°
C
Xfmr Thermal Capacity 1.00 kWh/°C
Wndg Thermal Time Constant 2.00 min
Energization Winding Source CT Bank 1 -J1
Year of Manufacture 1950
Setup

GE 845 Specifications

General

Brand	GE
Model	845
Category	Protection Device
Language	English