GE Industrial Solutions Entellisys System User Manual - Manual (Page 24)

System architecture 24
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1.3.18 UPS to HMI connection
The Entellisys system provides event/alarm/e-mail information when the UPS A has gone on
battery backup and when the batteries are low. When the batteries are low, the HMI safely shuts
down to avoid abrupt power interruption. To enable this communication, a link between UPS A
and the primary touchscreen HMI is established. This link is a serial connection between the
DB-9 serial port connection on the UPS and the DB-9 serial port connection on the HMI. Since
distances between the HMI and UPS may exceed serial cable distances, a pair of RS-232 to
RS-485 converters are installed at each end to accommodate the cabling distance through the
switchgear.
1.3.19 RS-232 to RS-485 converter
This device converts RS-232 signals to RS-485 signals. This is required to support the cable
lengths in the switchgear. RS-232 imposes a distance limitation of only 15 meters. RS-485 can
transmit data over distances up to 1.2 km.
1.3.20 Entellisys System Test Kit
The Entellisys System Test Kit is a portable test instrument designed for field testing of the
Entellisys Low-Voltage Switchgear system.
The test kit includes the following features:
• Simulate power-line characteristics for a single circuit breaker in the Entellisys Low-Voltage
System
• Verify the function/operation of the protection system
• Overcurrent protection tests – long time, short time, instantaneous and ground fault
protection tests
• Single point relay protection tests (overvoltage, undervoltage, over frequency, under
frequency, power reversal and phase loss, high current test)
• Verify the calibration of the trip time current curve
• Verify the operation of the circuit breaker actuation in “Trip mode”
• Perform tests without trips in “No Trip mode”
• Ground Fault Defeat function provides temporarily suspension of all ground fault protection
in the system
• Automatically retrieves system configuration for increased productivity
• Displays a summary of all protection configuration
• Saves test results to be reviewed later
• Windows Interface for ease of use
• Operation from 120 Vac
For more information, see DEH-233 Entellisys Low Voltage Switchgear System Test Kit User
Manual.
1.3.21 Clamp circuit
The clamp circuit is an intermediary device between the CTs with 150ampere and 400ampere
ratings only. The clamp circuit protects the Messenger from large current outputs from the CTs.
The clamp circuit is installed in the circuit breaker compartment on the left-hand side sheet.