Endress+Hauser EngyVolt RV15, Руководство по эксплуатации

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EngyVolt RV15 Appendix
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For low signal levels the noise contributions from the signal may represent a significant portion of
the “RMS of total waveform” and may thus generate unexpectedly high values of THD. In this case
the product will produce a display of 0 (zero). Typically, display of THD will only produce the 0
(zero) value when the THD calculation has been suppressed due to a low signal level being detected.
It should also be noted that spurious signals (for example, switching spikes) may be included in the
“RMS of the total waveform” and will be used in the calculation of THD. The display of THD may
be seen to fluctuate under these conditions.
11.1.7 Testing the phase sequence
The voltage and current inputs must be greater than 5 % of nominal for the test to operate reliably.
In the 3 phase 4 wire operating mode the measured values are referenced from L1.
For the voltage sequence test, the phase of L2 relative to L1 must be within the window 240 ±48
degrees and L3 relative to L1 must be within the window 120 ±48 degrees to record the sequence
V123.
Alternatively, the phase of L2 relative to L1 must be within the window 120 ±48 degrees and L3
relative to L1 must be within the window 240 ±48 degrees to record the sequence V132.
For the current sequence test, the phase of I1 relative to L1 must be within the window 0 ±48
degrees, I2 relative to L1 must be within the window 240 ±48 degrees, and I3 relative to L1 must
be within the window 120 ±120 degrees to record the sequence i123.
Alternatively the phase of I1 relative to L1 must be within the window 0 ±48 degrees, I2 relative
to L1 must be within the window 120 ±48 degrees, and I3 relative to L1 must be within the window
240 ±48 degrees to record the sequence i132.
In the 3 phase 3 wire operating mode measurements are referenced from L1-L2.
For the voltage sequence test, the phase of L2-L3 relative to L1-L2 must be within the window
240 ±48 degrees L3-L1 relative to L1-L2 must be within the window 120 ±48 degrees to record
the sequence V123.
Alternatively, the phase of L2-L3 relative to L1-L2 must be within the window 120 ±48 and L3
relative to L1-L2 must be within the window 240 ±48 degrees to record the sequence V132.
For the current sequence test, the phase of I1 relative to L1-L2 must be within the window 330
±48 degrees, I2 relative to L1-L2 must be within the window 210 ±48 degrees, and I3 relative to
L1-L2 must be within the window 90 ±48 degrees to record the sequence i123.
Alternatively, the phase of I1 relative to L1-L2 must be within the window 330 ±48 degrees, I2
relative to L1-L2 must be within the window 90 ±48 degrees, and I3 relative to L1-L2 must be
within the window 210 ±48 degrees to record the sequence i132.
11.2 Modbus implementation
11.2.1 Modbus protocol overview
In order to use the EngyVolt RV15 in a Modbus network, the optional RS485 / Pulse module is
required
This section provides basic information for interfacing a multifunctional electrical energy meter to a
Modbus protocol network. If background information or more details of the EngyVolt
implementation is required please refer to the following sections of this document. EngyVolt devices
offer the option of an RS485 communication facility for direct connection to SCADA or other
communications systems using the Modbus Protocol RTU slave protocol. The Modbus Protocol
establishes the format for the master's query by placing into it the device address, a function code
defining the requested action, any data to be sent, and an error checking field. The slave's response
message is also constructed using Modbus Protocol. It contains fields confirming the action taken,
any data to be returned, and an error-checking field. If an error occurs in receipt of the message, the
device will make no response. If the device is unable to perform the requested action, it will construct
an error message and send it as the response.