Using pas, Device inputs, Ac inputs – SATEC PM180 Operation Manual User Manual
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Chapter 2 Device Description
Device Inputs
PM180 Substation Automation Unit
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The remote display modules communicate with the PM180 using the MODBUS RTU
protocol. Both the COM3 port and the RDM/RGM RS-485 port are preset at the
factory to 19200 bps, 8-bits/No-parity, address 1, and run the MODBUS RTU
protocol. The baud rate can be increased up to 115200 bps (depending on the
communications quality) through the RDM or service Terminal program.
Using PAS
PAS is the support software supplied with the PM180 that gives the user basic tool
for programming the device, performing remote control operations, monitoring real-
time measurements, retrieving and analyzing historical data files, reviewing fault and
power quality reports, and more.
PAS can communicate with the devices through any PM180 port using the MODBUS
RTU, MODBUS ASCII and DNP3.0 protocols.
For information on installing and using PAS, see Chapter 6 “
Device Inputs
AC Inputs
The AC voltage and current input terminals are connected to the internal device
circuits through input transformers that isolate the device from external wiring.
Voltage Inputs
The device has three transformer-isolated and one high-impedance voltage inputs
(direct 690V RMS phase-to-phase voltage, ×120% overload). Voltage channels are
designated as V1 through V4.
The secondary voltage rating and primary to secondary voltage ratio (PT ratio) of the
external potential transformers must be specified in your device to provide correct
voltage measurements. For more information on specifying voltage input ratings in
your device, see
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 100A current transformers (5A rated
current) as a standard.
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, and the second is the extended current range up to 100A, used for
measuring and recording fault currents.
For more information on specifying input ratings in your device, see
Sampling
All 8 AC channels (4 voltages and 4 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