Stop start retain relay control circuit for an ac machine

Electronics Module

Note: Copy and paste these cover and task sheets to the front of your written work as you must sign (electronic signature) and date these in order to have your assessment marked and graded

Task 1 [P1]

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 50m conveyor used to transport product in a cleanroom between process steps. The conveyor also contains a number of elevators protected by guarding. The 2nd piece of equipment is a mixing tank agitator driven by an induction motor controlled by an inverter. The tank is made of stainless steel and contains acidic chemicals when in use.

As part of the review you will need, for each apparatus, to explain and identify the hazards that exist when a planned maintenance (PM) is being carried out. These are risks posed to anyone in the area, not just the Technicians carrying out the PM. In particular focus on electrical hazards

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. In particular give a detailed range of control measures to prevent/reduce the risk of electric hazards

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 with reference to at least 4 pieces of safety legislation, regulations or standards, and how these might apply to the PM activities described in task 1

Task 4 [P9]

From the 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 and lathe in the workshop that must include 2 emergency stop positions. Also explain how the circuit would operate and what types of commercial relays/contactors could you select.

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 diagrams and research evidence, the operational features system for an AC drive system with variable speed control.

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 using a DC motor drive system. With reference to circuit layout drawings and research sources, explain how it operates.

Task 7 [M3]

A new robot cell has been installed to operate along with the conveyor system above. You have been asked to:

a) Describe with the aid of diagrams, the operation of a safety relay system used on a robot cell. (400 words)

b) Explain how this system addresses the hazards and control measures by also referencing relevant legislation, regulations or standards. (400 words)

Task 8 [D2]

To ensure that the conveyor system is safe and complies with legislation, compare the construction and operation of two different types of stop/start/retain relay control circuits for suitable for either the AC or DC system in task 5 or 6.

For example you may compare an electro-magnetic relay system with an electronic logic system. Include appropriate drawings, parts, truth tables and their advantages/disadvantages in your explanation.