SATEC SA300 ezPAC Operation Manual - Manual (Page 16)

Chapter 2 Device Description Device Inputs
16 SA300 Substation Automation Unit
The secondary rating of the voltage inputs is used as a reference for calculating
thresholds for the power quality and fault triggers.
Current Inputs
The device is provided with current input transformers with either 5A or 1A rated
current.
All models are shipped with four extended range 150A current transformers (5A rated
current) as a standard, and the SA330 “Premium” device has four additional 20A
(ANSI) or 10A (IEC) current transformers (5A rated current) that can receive currents
from separate external CTs.
To expand the dynamic range of the current inputs, current measurements are
performed in two measurement ranges regardless of the device model: one is the
standard current range up to 20A/10A for precise power, energy and harmonics
measurements (current channels are designated as I1 through I4), and the second is
the extended current range up to 150A, used for measuring and recording fault
currents (current channels designations are I1x through I4x).
In the SA330 “Premium” device, the standard 20A/10A measurements and extended
150A measurements are taken from separate current transformers. In the SA310 and
SA320, both standard and extended range measurements are taken from the same
150A current input terminals.
The following table shows the relationship between the device input terminals and
current measurement channels.
Device Input
Terminals
Current
Channel
Description
SA310, SA320 I1-I4 I1-I4 Standard range AC currents - 10A/20A range
SA330 I5-I8 I1-I4 Standard range AC currents - 10A/20A range
SA310, SA320, SA330 I1-I4 I1x-I4x Extended range AC currents - 150A range
In the SA330, the primary rating for external current transformers can be set
independently for the standard current range channels (CT primary, I4 CT primary)
and extended range channels (CTx primary, I4 CTx primary). For more information on
specifying input ratings in your device, see
2
Basic Device Setup in Chapter 7.
Sampling
All 12 AC channels (4 voltages and 2x4 currents) are continuously and
simultaneously sampled at a rate of 128 samples per cycle (6.4 kHz at 50Hz or 7.68
kHz at 60Hz).
The sampling rate is precisely synchronized with the power frequency. The reference
frequency signal is taken from one of the phase voltage inputs V1-V3, band-pass
filtered, and then sampled at 12.5 MHz providing a 0.0004% cycle measurement
error.
Waveform Tracing
The sampled waveforms are stored to the circular trace buffer whose depth is
sufficient to provide up to 20 pre-fault cycles for the waveform recorder. The
waveform recorder is synchronized with the sampling circuitry and can store unlimited
number of post-event cycles. The length of the captured waveforms is only restricted
by the size of the allocated logging memory.
VDC Input
One isolated DC voltage input (300VDC range) is normally intended for monitoring
the substation battery. It is sampled at a rate of 2 samples per cycle (each 8 or 10
ms) and synchronized to the AC sampling circuitry.
The waveform recorder can provide recording of VDC data simultaneously with the
AC input channels that allows testing the behavior of the substation battery under
load at the time of a fault.