Scenario for tasks 1-3
The Maintenance Manager has asked you to review the planned maintenance (PM) procedure for 2 pieces of equipment in the factory.
- The 1st piece of equipment is a conveyor system used to transport product between process steps. The conveyor also contains a number of elevators driven by 230 v ac/dc speed control drives and dc brushless motors. Various sensors are used to control the motors via PLCs.
- The 2nd piece of equipment is a mixing tank agitator driven by a 400v induction motor controlled by a variable speed drive. The tank is made of stainless steel and contains acidic chemicals when in use.
Task 1 [P1]
As part of the review you will need, for each apparatus, to identify the hazards (together with the activity) that exist when a planned maintenance (PM) is being carried out for each machine. These are hazards posed to anyone in the area, not just the electrical technicians carrying out the PM. So include the person(s) and how their activity exposes them to the hazards. Give at least 2 mechanical and 2 electrical hazards for each machine (8 in total, with none of the 4 electrical hazards being the same).
Guidance: These shall be given in the form of a risk assessment along with task 2 control measures using the RA spreadsheet template provided on Moodle.
Checklist of evidence required: T1 –(Snip) Image of risk assessment and copy of spreadsheet
Task 2 [P2]
From the information in task 1 you must also specifically list the control measures required to eliminate or manage the risks to the Maintenance Technicians and others.
Guidance: In particular give a detailed range of control measures to prevent/reduce the risk of the hazards given in task 1. This should be done by assessing the hazards/risks and existing controls using the RA spreadsheet template and updated with additional controls as appropriate
Checklist of evidence required: T2 –(Snip) Image of risk assessment and copy of spreadsheet
Task 3 [P3]
A quality and safety audit is to be carried out on all the maintenance procedures in the factory. The Maintenance manager has asked you to describe with reference to 4 different pieces of safety legislation, regulations or standards, how these might apply to the 4 electrical activities/hazards described in task 1
Guidance: You should apply different legislation/BS specifically to the above case study (not generally) and by referencing specific regulations legislation or standards e.g. Activity 1: (electrocution / safe isolation) ref- E@WR Regs 4(3) and 12(1b) (400 words), Activity2 – BS7671:2018-(531.3), etc
Checklist of evidence required: T3 –400 word written report with specific references
Task 4 [P9]
From workshop audit you have been asked to:
- Draw a start/stop/retain relay control circuit that could be used for the safe and emergency operation of a 3-phase drilling machine or lathe in the workshop.
- Describe how the circuit and relay/contactor would operate for the machine. Include the principles of operation for electro-magnetic-mechanical relay.
- Describe with an example, what types of commercial relays/contactors could be selected for the task.
Guidance: 4a. Circuits must show control & 3-ph, and include 2 emergency stop positions in addition to the normal start/stop. Provide evidence of an appropriate commercial relay with a copy of an extract of its specifications and not a just a reference(300 words)
Checklist of evidence required: T4 –300 word written report and technical diagram with appropriate examples
Task 5 [M1]
The production manager also wants your help in deciding the best type of motor system for controlling the speed of a new automatic conveyor line. He has asked you to explain with the aid of a diagram, example and research evidence, a variable speed drive (VSD), in particular
- the operational features (how it works with a circuit diagram)
- how it can be applied a conveyor (with a schematic diagram of a VSD connected to a conveyor)
Guidance: Requires a schematic/circuit diagrams of the conveyor installation and key elements of an electronic VSD. Application should also show and an extract (snip copy/paste) of a suitable commercial VSD (400 words)
Checklist of evidence required: T5 –400 word written report and technical diagrams with appropriate examples
Task 6 [M2]
As an alternative to the AC system in task 5, you have also been asked to produce a circuit design that can control the speed and direction of the conveyor such as an AC to DC motor thyristor and transistor H-bridge drive system. With reference to appropriate diagrams, an example and research evidence discuss
- the operational features (how it works with speed and direction circuit diagrams)
- how it can be applied a conveyor (with a schematic diagram of the controller connected to a conveyor)
Guidance: Requires schematic/circuit diagrams. Select electronic drive/controls rather than mechanical relays and resistors (400 words)
Checklist of evidence required: T6 –400 word written report and technical diagrams with appropriate examples and references
Task 7 [M3]
- with the aid of a robot cell layout, the operation of a safety relay system used on a robot cell in the diagram shown: (start with closing the door and pressing the start button). (200 words)
- how this system addresses the hazards and control measures by also referencing relevant legislation/standards such as the Machinery Directive/Regs or IEC61508. (300 words)
Guidance: for 7a:You should have a diagram of the robot cell highlighting the types of safety devices, followed by a diagram on how a safety relay can be electrically connected to these devices in order to control them (at least 3 devices). For 7b legislation should follow the machinery directive and any specific regulations that apply to robot cells
