GE C70 Instruction Manual page 29

CHAPTER 2: PRODUCT DESCRIPTION
An analog low pass anti-aliasing filter with a 3 dB corner frequency is set at 2.4 kHz and is used for current and voltage
analog filtering as well as signal conditioning. The same filtering is applied for phase, ground currents, phase-to-phase
(when applicable), and auxiliary voltages. The 2.4 kHz cut-off frequency applies to both 50 Hz and 60 Hz applications and
fixed in the hardware, and thus is not dependent on the system nominal frequency setting.
The UR samples its AC signals at 64 samples per cycle, that is, at 3840 Hz in 60 Hz systems, and 3200 Hz in 50 Hz systems.
The sampling rate is dynamically adjusted to the actual system frequency by an accurate and fast frequency tracking
system.
The A/D converter has the following ranges of AC signals:
Voltages:
Currents:
Current harmonics are estimated based on raw samples with the use of the full-cycle Fourier filter. Harmonics 2nd through
25th are estimated.
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
Figure 2-3: UR signal processing
SIGNAL PROCESSING
2
Eq. 2-1
Eq. 2-2
2-15