Importance of Health and Safety with Programmable Controllers

This research paper focuses on the critical importance of health and safety when working with programmable controlled equipment (PCEs), industrial equipment used for manufacturing control. The paper highlights the potential for malfunctions and errors in PCEs, emphasizing the need for safety measures such as emergency stops and power-off mechanisms to prevent accidents. It details the connection methods for normal start/stop buttons and emergency stop buttons, explaining the differences between them and the importance of fail-safe designs. Furthermore, the paper includes a sketch of a hard-wired emergency stop system, emphasizing its independence from the PLC for safety. Finally, the paper outlines essential troubleshooting steps for malfunctioning PCEs, including power removal, sensor checks, connection inspections, and software version verification. The paper concludes by summarizing the key points and reinforcing the significance of health and safety in the context of programmable controlled equipment.

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HEALTH AND SAFETY
A Research Paper on PLC By
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INTRODUCTION
This is a research paper on the importance of health and safety when an individual is
working with a programmable controlled equipment. A programmable controlled equipment
is an industrial equipment which has been ruggedized and adapted for the control of the
process of manufacturing such as robotic devices and assembly lines.
Describe the importance of health and safety when working with programmable controlled
equipment
The programmable controlled equipment is prone to malfunction or failure when
functioning since the software program is written by a team or an individual. There is a high
chance of errors occurring on the equipment in both the interpretation and in specifications by
the programmer. The programmable controlled equipment has systems to ensure health and
safety such as emergency stop, turning off of power supply, and removal of hydraulic
pressures. Hence, there is need of ensuring health and safety when working with
programmable controlled equipment to prevent accidents which might be caused by faults in
the equipment leading to damage of the equipment and also injury to the users (Bryan, 2015).
Describe the method for connecting a normal start or stop buttons and an emergency stop
button used in potentially dangerous machinery. Explain the important differences between
the two connection methods.
Every machinery has a normal start or stop button which are used in starting the
normal operations of the machine or stopping the machinery after completion of the task at
hand. The normal start button is normally green in colour and is used in sending logical
instructions to the PLC to begin its operations. The stop button is usually red in colour and is
used in sending logical instructions to the PLC to stop its operations. The emergency stop
button is applied during the performance of a PLC and its work is to send logical instructions

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to the PLC for the terminations of the working process of the machine (Davies, 2012). The
method of connecting the normal star or stop button is as shown in the figure below:
From the circuit above, the Boolean instructions in the program of programmable
logic equipment will give a particular address which is either fed to the pins xo or x1. This is
the address of a single bit of Boolean instruction and can either be 1 or 0 depending on the
intended instruction. When an instruction address is given at either of the inputs, the state of
the instruction will be represented as the state of the input and the PLC will respond
accordingly. In the circuit above, when the start button is pressed, the PLC will begin
functioning normally since the current will be flowing in the circuit (Fisher, 2016).
The stop button will send the instruction to the system to stop functioning. In this
circuit, there is system will continue working in case there is an emergency. The safe way of
connecting the circuit is to use the normally closed switch as shown in the figure below:
When the normally closed switch is used in the circuit when any fail such as wire
breaking occurs, the input will act as the normally closed switch, hence is the wire to the stop

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button breaks, the similar scenario will take place as if the stop button has been activated.
There will be breaking of the latch (Frederickson, 2010).
Make a sketch of a common hard-wired emergency stop system for a system that includes a
programmable controller.
An emergency stop system is a circuit wired with the programmable controller which will be
involved in system shutdown in case of detection of potential danger on the system of the
user. The button of the emergency stop, as well as switches of the safe guard, should be
hardwired and not depending on the programmable controller for its implementation. The
safest way of connecting a common hardwired emergency system to provide safety of the
programmable controller is as shown in the sketch below:
From the sketch above, it is clear that the hardwired emergency system is outside the
programmable logic controller and hence it does not depend on the programmable controller
for its implementation. In the connection above, the system is safe from failures and errors
that might occur. Is an error of failure occurs, the outputs of the PLC must be reverted to a
fail-safe mode so that no harm can take place. The guards on a machine should not be in a
position to open or be opened in there is a failure in the PLC (Robert, 2011). In the circuit,
the stop instruction will be provided by the switch. For the safe system of an emergency stop,
there is need of providing a signal of stoppage if there is an error or failure and the switch
should not be operated. This is due t the possibility of the problem happening in the PLC,

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hence there is need of operating the emergency stop independent with the PLC (Michel,
2012).
In the event of a programmable control system not running correctly, give a list of four
actions that you would take to remedy the situation.
Some of the reasons that may cause the programmable control system not to function
correctly include communication failure, module failure, input-output faults, main power
failure, and input-output failure. In case of any detection of the failure in the system, there is
need to take actions to solve the situation such as:
Remove the power: The first procedure to take in case of failure of the system is to terminate
the current flow in the system by stopping the machine. This can be done by using the
emergency stop button or using the mains switch. This step will ensure that no further
damages happen on the equipment (Fisher, 2014).
Checking the operation of sensors: All the sensors should be checked to ensure that there are
properly functioning without any faults or damage. This can be done by the use of the
diagnostic process of sensor testing.
Checking the Connection: Once the power has been cut off, the system will then be safe for
inspection. The cables and connectors can then be checked to find out if any cable was
incorrectly placed. Continuity of the cables can also be checked to ensure that there is free
flow of current and signals.
Checking the Software version: The software used in the PLC is prone to be corrupted by a
virus attack. Hence there is need to constantly update the version of the software to run the
system to prevent any attacks. If the software is corrupted, then it should be installed and the
latest version of another software be installed. The errors logs should also be checked to
ensure correctness in the data transmission (Sammarco, 2013).

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Conclusion
This research paper is about the importance of health and safety when an individual is
working with a programmable controlled equipment. A programmable controlled equipment
is an industrial equipment which has been ruggedized and adapted for the control of the
process of manufacturing such as robotic devices and assembly lines.

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Bibliography
Bryan, A., 2015. Programmable Controllers. Melbourne: Theory and Implementation, Industrial Text
Co.
Davies, P., 2012. Microsoft remote software “kill switch” confirmed. London: SlashGear.
Fisher, J., 2014. Safety framework for programmable electronics in Mining. New York: Society of
Mining Engineers.
Fisher, J., 2016. Programmable electronic mining systems: best practice recommendations. Paris:
Pittsburgh.
Frederickson, A., 2010. Comparison of programmable electronic safety-related system architectures.
Perth: http://www.safetyusersgroup.com/info_service/default.asp?cat_id=1.200.
Michel, G., 2012. Programmable Logic Controllers: Architecture and Applications. London: John Wiley
and Sons.
Robert, R., 2011. Designing with E-stop switches. Colorado: machinedesign.com.
Sammarco, J., 2013. Programmable electronic mining systems. Michigan: System safety.