GE B30 Instruction Manual page 352

5.9 TRANSDUCER INPUTS AND OUTPUTS
The minimum and maximum voltage values to be monitored (in pu) are:
minimum voltage
The following settings should be entered:
DCMA OUTPUT H3 SOURCE
DCMA OUTPUT H3 RANGE
DCMA OUTPUT H3 MIN VAL
DCMA OUTPUT H3 MAX VAL
The limit settings differ from the expected 0.7 pu and 1.1 pu because the relay calculates the positive-sequence quantities
scaled to the phase-to-ground voltages, even if the VTs are connected in "Delta" (see the Metering Conventions section in
chapter 6), while at the same time the VT nominal voltage is 1 pu for the settings. Consequently the settings required in this
example differ from naturally expected by the factor of
The worst-case error for this application could be calculated by superimposing the following two sources of error:
• ±0.5% of the full scale for the analog output module, or
• ±0.5% of reading
For example, under nominal conditions, the positive-sequence reads 230.94 kV and the worst-case error is
0.005 x 230.94 kV + 1.27 kV = 2.42 kV.
5
5-218
161.66 kV
-------------------------- - 0.404 pu,
= =
400 kV
: "SRC 2 V_1 mag"
: "0 to 1 mA"
: "0.404 pu"
: "0.635 pu"
3
B30 Bus Differential System
254.03 kV
maximum voltage -------------------------- -
=
400 kV
.
± 0.005 × ( 1 0 ) × 254.03 kV
–
5 SETTINGS
0.635 pu
(EQ 5.27)
=
± 1.27 kV
=
GE Multilin