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  • Understanding safety functions: Fluctuations, loss and restoration of power sources

    Control systems must be protected against fluctuations and power loss, whether electrical or fluidic. Fluctuations and losses are well defined in IEC, IEEE and ISO standards. Careful design of electrical systems, including the use of UPSs for electrical control systems and the careful design of pneumatic supply systems, including the proper sizing of pneumatic accumulators for compressed air-powered logic, is essential.

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  • Understanding safety functions: Pressure or temperature

    Pressure and temperature are important safety-related parameters. The two parameters are closely linked in systems where gases or vapours are present, with behaviour governed by the combined gas laws. The temperature is also critical in mechanical systems that can overheat, like motors or bearings. Monitoring temperature or pressure requires the correct selection of instruments.

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  • Understanding safety functions: Safe speed and safe standstill

    In this post, I’ll discuss two safety-related parameters: safe speed and safe standstill. Speed control is a very common machine function. Conveyors, mixers, pumps, and many other applications rely on variable-speed drives. Some speed parameters are also safety-related because variations in speed can increase the risk to workers. See this post for more information on…

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  • Understanding safety functions: Response time

    This post deepens the discussion of safety-related parameters. Safety functions are control functions whose failure causes an immediate increase in risk. ISO 13849-1 [1] defines several common safety functions to develop safety-related control systems. In this post, I will discuss the response time safety-related parameter. Related posts: Emergency Off (EMO) vs Emergency Stop Interlocking Devices:…

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  • Understanding safety functions: Safety-related parameters

    Safety-related parameters are control system variables whose incorrect setting immediately increases the risk to the user. Some of the most common include safe-reduced speed and safe standstill, but temperature, pressure and other process parameters can also be safety-related. Defining what machine parameters are safety-related and then designing control hardware and software to meet the functional…

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  • Understanding safety functions: Local control

    The local control function is important to understand when designing machinery control systems. If the failure of the local control function could lead to increased risk to the user, it is a safety function. This article explains the local control function from a functional safety perspective.

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  • The Industrial S-Word

    The Industrial S-Word is a new podcast covering industrial equipment safety hosted by Matt Ernst. Matt has many years of experience in the industrial automation sector, from his early days in 2006 with WIKA Instruments Canada Ltd., to his current work with Schmersal Canada. Last week I had the great pleasure of being interviewed by…

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  • The Westray Mine Disaster

    Today is the 30th anniversary of the Westray Mine disaster in 1992. At 5:18 am on Saturday, May 9, 1992, a great, blue flame flashed out of the mine opening, a cloud of black smoke on its tail [1]. Twenty-six miners lost their lives when a methane and coal dust explosion destroyed the mine. Eleven…

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  • Canada’s National Day of Mourning

    Fight for the Living, Mourn for the Dead On April 28th, Canada’s National Day of Mourning, we mourn for our workplace dead. According to the WSIB, in 2020, 245 people died from a work-related injury or illness in Ontario [1]. Workplace deaths have broad and deep effects on workers’ families, employers, and society. Workplace fatalities…

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  • CSA Z432 Public Review Open!

    CSA Z432 Public Review is open. If you are a user, a builder of machinery, or an evaluator of machinery, this is your opportunity to see the draft of this important standard and to make comments to help the Technical Committee improve the standard on your behalf. Note: The start of the public review period…

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