STC Smartscan NG2, Руководство пользователя

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May 2021, SmartScanNG² User's Guide for Wayside Enclosure Components, EUD-2018086-00 Rev.3
2.3.2 SOTC Board (Zepic PD8-Plus)
If your system uses advance transducers for presence detection, skip ahead to the next
section.
The SOTC board tells the system when a train is present at the site. On the board is the blue
calibration switch, which is used to adjust the gain control of the track circuit. See Section
10.7 Calibrating the Zepic III Presence Detector.
The SmartScanNG² chassis only has a SOTC board if the site is using a track circuit. If the
site is using two advance transducers, there is no SOTC board.
2.3.3 Relay Panel
The SmartScanNG² system uses optically isolated solid-state relays (SSRs) to eliminate
electromagnetic radiation, which would otherwise be generated by arcing of mechanical relay
contacts. There are three SSRs mounted to the relay panel. One SSR operates the scanner
shutters, and another energizes the scanner heaters. The signals to activate the SSRs
originate at the Processor board.
A third SSR is used to monitor and flag AC power failures. If AC power is disrupted, a
message will be posted to the Event Log, and "AC Power Off" will appear just before the menu
header in the Serial Interface. If the AC power is off when a System Status report is
requested, the message "AC Power Off" will be printed in the System Status report. If the AC
power is off when a train passes the site, the message "AC Power Off" will appear in the
System Alarms section of the Train Detail report.
The power rating for each SSR is intentionally overrated to ensure long-lasting reliability. For
example, the SSR associated with the scanner
shutters is rated for 100 VDC at 12 amps,
even though the shutters operate on 12 volts and require less than 2 amps each. Likewise,
the SSR associated with the
heaters in the 2500-512 DC scanners is rated for 100 VDC at 12
amps, even though the heaters operate on 12 volts and require less than 1 amp each. The
SSR associated with the
heaters in the 2500-512 AC scanners is rated for 240 VAC at 25
amps of current, even though the heaters require only 120 VAC at 1.6 amps each.