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.

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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

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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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