Success story PLC€¦ · Unitronics PLC+HMI all-in-one controllers enabled an important...
Transcript of Success story PLC€¦ · Unitronics PLC+HMI all-in-one controllers enabled an important...
The University of Johannesburg’s School of Engineering and the Built
Environment strives to prepare students for their future careers and give them
hands on engineering experience. Johan Meyer, an associate professor in the
engineering department, and Rene Naidoo, an undergrad in her final year of an
electrical and electronics engineering degree, set out to undertake a community
service project, a common requirement at South Africa’s colleges and
universities. Johan Meyer saw an opportunity to not only participate in this
program, but also to solve a key problem with these service projects.
With many of these community service projects and philanthropic projects, there
is a “give and forget” mentality. One-off donations are installed, but no one
maintains or provides on-going support and maintenance; projects fall into
disrepair and the recipients are either back to square one or they need to cover
costly repairs out of pocket. Johan Meyer believed that integrated automated
control and monitoring technology to his community service project, he could
break the “give and forget” cycle.
The primary goal of the project was to bring clean drinking water using solar
power to Gwakwani, a remote, rural village. The village’s water supply had been
provided by a diesel powered pump over a decade old; however, the villagers
needed to provide the diesel, leading to shortages due to cost and transportation
concerns. To ensure a reliable energy source, and a reliable source of clean
water, Meyer installed a solar powered borehole pumping system. The pump
sits in a depression, connected to a storage tank at the top of the depression
roughly 500 meters away. A second solar electricity supply was installed to
power floodlights for security purposes and to create a charging station
for the villagers’ cell phones.
ALL IN ONE
PLCHMI
Unitronics PLC+HMI all-in-one controllers enabled an important improvement to philanthropic endeavors
Success storyIndustry: Pumps
How can you install a PLC with remote monitoring and control in an area without electricity?
A team from the University of Johannesburg’s School of Engineering worked on a service project to bring clean drinking to a remote village. They believed that by implementing automation and remote monitoring technology they could prevent a “give and forget” effect, where service projects fall into disrepair after a few years.
Using two Unitronics PLC+HMI units, they were able to control a solar powered water pump, record data on the pumps performance and report the status of the pump via cellular communications. These versatile PLCs made it easy for the team at University of Johannesburg to ensure that the water pump continued operating at optimal levels long after the initial installation.
Summary:
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Johan Meyer
ALL IN ONE
PLCHMI
Because Gwakwani has cellular coverage, Meyer and his team were able
to create a remote monitoring and control system, to prevent the “give
and forget” effect. Onsite the system is controlled by a Unitronics Jazz
PLC, interfaced with pressure and flow sensors, which also controls the
lights and charging station. Because the water tank was separated from
the pump, it didn’t have its own power supply for a sensor to measure the
water level directly. As a work around, the water level is estimated by
measuring the feedline static water pressure and compensating for the
elevation gain between the pump and the tank. A DC current sensor was
installed to measure the current between the solar panels and the pump.
In order to monitor the status of the power supply to the PLC itself, the
sensors measure the battery voltage, the battery temperature and the AC
output current of the main inverter.
To make sense of all the information collected by the Jazz PLC, the PLC,
configured as a Modbus slave, transmits the data using a radio modem to
a radio to cellular interface station. Once the data is converted to a signal
on the cellular network, it is transmitted to a second PLC, configured as a
Modbus master, via a GSM modem. This PLC, a Unitronics Vision1210,
is installed at the University of Johannesburg, where it displays the status
of the pump, power supply and tank.
Trend analysis of water pressure over time allows Meyer to create models
to determine the village’s water usage over time. The Vision1210 also
tracks water flow rate as a function of solar pump current, which allows
the team to monitor the pump health and detect any problems before the
pump fails. Similarly, they monitor the battery voltage and temperature
over time to ensure that the battery is not losing efficiency or in danger of
overheating. All this data is displayed clearly on the integrated HMI
panel.
This connectivity was vital to avoiding the “give and forget” effect. If any
of them fall outside the normal operating range, the Vision1210 triggers
an alarm to notify Meyer and his team. They can turn off aspects of the
system, like the floodlights to preserve battery life, from the Vision1210
PLC or dispatch someone to perform necessary maintenance before a
major problem or breakage occurs.
Unitronics PLC+HMI all-in-one controllers enabled an important
improvement to philanthropic endeavors. The Jazz and Vision1210 have
excellent communication options, particularly Modbus and GSM
modems, allowing the pump and solar panels to be monitored and
controlled remotely. The communication configuration, ladder logic and
HMI design are all programmed in a single software environment.
Unitronics also offer software utilities that make data trends and data
export easy to configure and effortless to use. Furthermore Unitronics’
all-in-one PLCs are available in a broad range of sizes and
configurations. The Jazz unit used for the onsite control is a small PLC
with onboard I/O and a basic text display and keypad HMI, while the
Vision1210 for remote monitoring has an integrated 12.1-inch color,
touchscreen HMI.
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