7.17
Date Code 20080918 Instruction Manual SEL-749M Relay
Communications
SEL ASCII Protocol Details
SEL-749M Date: 12/10/2003 Time: 08:56:03.190
MOTOR RELAY Time Source: external
=>
If no IRIG-B code is present at the serial port input or if the code
cannot be read successfully, the relay responds:
IRIG-B DATA ERROR
=>
If an IRIG-B signal is present, the relay synchronizes its internal clock with
IRIG-B. It is not necessary to issue the IRI command to synchronize the relay
clock with IRIG-B. Use the IRI command to determine if the relay is properly
reading the IRIG-B signal.
L_D Command (Load Firmware)
Use the L_D command to load firmware. See Appendix A: Firmware and
Manual Versions for information on changes to the firmware and instruction
manual. See Appendix B: Firmware Upgrade Instructions for further details
on downloading firmware.
Only download firmware to the front port.
METER Command
The MET commands provide access to the relay metering data. The relay
divides the displayed information into two groups:
NOTE: All ASCII command responses
in this section are examples only. Your
specific relay will have differences
based on model number, firmware
revision number, and application.
➤ Instantaneous
➤ Thermal and RTD
METER k (Instantaneous Metering)
The MET k command displays instantaneous magnitudes (and angles, if
applicable) of the measured and calculated analog quantities.
All angles are displayed between –180 and +180 degrees. For delta-connected
PTs, angles are referenced to VAB or L1. For wye-connected PTs, angles are
referenced to VAN or L1. If the voltage channels are not supported, or
VAB < 13 V (for delta) or VAN < 13 V (for wye), angles are referenced to L1
current.
To view the instantaneous meter values once, use the MET command (see the
example in Figure 5.1). To view the meter values k times, use the MET k
command, where k is a number between 1 and 32767.
Table 7.27 L_D Command (Load Firmware)
Command Description Access Level
L_D Download firmware to the control. 2
Table 7.28 METER k (Instantaneous Metering)
Command Description Access Level
MET k View/reset relay measured quantities 1
Courtesy of NationalSwitchgear.com
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