|
|
|
Environmental Supervisory System in communication machine room
The procedure of
such system is: Each machine room is equipped with a RTU to collect
various data in the room, including the power supply, or DC voltage
value of -48V and -24V accumulator, or the voltage of AC220V, the
temperature, the humidity, the fire alarm, the access control, the air
conditioning and equipment alarm, etc. After collection, the RTU then
send the data to the computer in master station.
This procedure consists of 3 parts:
1) Data acquisition
This action is carried out by RTU. A RTU should have 2 power
supplies at least, the -48V DC and the 220V AC, so that it can offer 1+1
power redundant to ensure the normal running when one power supply
fails.
2) Transmission
As the function requirement, the SCADA system should have
higher stability than the communication equipment in the machine room,
and it depends mainly on the power supply and transmission port.
The best method is using 2M interface (E1). The E1 should be SDH
equipment channel, and due to the self-healing protection of SDH system,
the communication can be retained even when the fiber cable broke.
But most SCADA engineers and companies who are not familiar with telecom
and do not know E1 structure and characteristics usually adopt serial
port (e.g. RS232, RS422/RS485) for transmission. And the most
disadvantage of such port is the obvious vulnerability. Any of the
lightening, high voltage, the current surging, short circuit and
grounding can cause damage to the port. This shortens the life span of
most SCADA system.
And Ethernet is also a good choice for communication, and it is limited
by lack of Ethernet port in machine room.
3) Software for main station
server
For data transmission and display of the RTU under
administration, data form or graphics can be adopted for statistics
statement generation.
It is important that when one server is connected with numbers of RTU, a
particular equipment, is needed to connect with both the server and SDH
system. This can be completed by an Ethernet switch or a PCM30 device
with cross-connect function and multiple E1 interfaces, which can
connect the time slots in different E1 interfaces with the serial port
of the computer (the server).
|
|
|
工程实例
|
|
Hengguang Technologies, which founded in 1993 as
a manufacturer of fiber optic supervisory system, engaged in the
application of optical supervisory system in SCADA system since 1995.
The following systems are typical SCADA systems made by Hengguang
Technologies.:
-
Jieyuan Water Supply SCADA system of Tianjin
-
SCADA systems
for No.1 Waterworks, No.2 Waterworks and No.3
Waterworks of Dezhou Water Supply Company
-
SCADA system for the 170 bases of Qingdao Post and Telecom Bureau
-
SCADA for Jiuquan Satellite Base, SCADA for Pingdingshan Coke
Plant, etc
The Jieyuan Water Supply SCADA system of Tianjin, completed in 1996,
Have served well more than ten years before its out of commission. The
waterworks of Dezhou Water Supply, which had be put to use in 2000, have
been working till today without any error. All the projects above have
more than ten sites needing supervision in the system. |
|
