Motor failure is a disproportionally large contributor to costly downtime in businesses across industries. Anmol Joneja of Schneider Electrics proposes coordinated motor starter schemes that address this problem.
17 December, 2018
We all know that downtime for any business can be expensive, even devastating. But did you know the cost of downtime is rising?
Aberdeen Group reports that, on average across all industries, downtime costs are up from USD 164,000 per hour in 2014 to USD 260,000 per hour in 2017. That’s an increase of 60 per cent in just three years!
When it comes to downtime, motors are a disproportionally large contributor compared to other causes, simply because motors are used in so many processes, from pumping to material management. So, a failure in a motor will have a serious ripple effect on productivity.
The most common failure mode for a motor is when it is under excessive load. Such a condition causes an increased draw of current, which then causes overheating. It’s this overheating that causes the undue wear on motor components that ultimately results in failure.
However, it’s short circuits in motors that pose the greatest dangers for the equipment, the installation, and for personnel. There are a few possible sources, but any short circuit can cause a sudden and massive surge of current within milliseconds that can melt and destroy contacts, produce electrical arcs and even explosions.
Short circuits can not only cause physical damage – they can easily lead to catastrophic fires. In fact, it’s estimated that 60 per cent of fires are due to short circuits.
The International Electrotechnical Commission (IEC) has recognised that electrical faults in motor control are a critical situation that needs to be properly addressed to ensure the safety of personnel and equipment, as well as productivity of an installation. Therefore, the IEC has developed specific standards and testing procedures to ensure that the combination of devices used to control motors – i.e. motor starters – is safe. This is achieved through ‘coordination’.
A ‘coordinated starter’ is a tested combination of short circuit protection devices (e.g. fuses or circuit breakers), switching devices, and overload protection devices. The motor starter combination is tested under extreme conditions and is required to clear the fault quickly, without damage to the installation or risk to the operator. This makes it the optimum, tested combination of devices to ensure safety.
There are two types of coordination included in the International Electrotechnical Commission’s IEC 60947-4-1 standard: Type I and Type II.
Let’s have a look at how each of these is defined.
This coordination level provides a basic solution, which balances uptime and cost-effectiveness. It’s a good choice when machine uptime is not a priority, as this level does not provide continuity of service. Also, there are associated maintenance costs. Before restarting, replacement of the starter is recommended
This is a high-performance solution, providing reduced machine shutdown time and reduced cost of equipment replacement. The motor starter must be ready for reuse after a fault, with only a simple inspection required. Contacts may become welded but are easily separated.
This is the highest possible performance, ideal for mission-critical operations and processes. There is no damage to the equipment, and following the fault, the starter must be immediately reusable. No resetting is required, and no inspection is needed. Therefore, the installation can return immediately to operation. This level of coordination is listed under a different standard, as it is defined for combination devices with multiple functions.
You can see that these levels of coordination enable a range of benefits, from protecting people and equipment to permitting a greater continuity of service, to reducing maintenance costs by avoiding the time and cost of replacing equipment. Given the increasing costs of downtime and machine or process failures, it’s clear that the coordination of motor starters is moving from a choice to a necessity, as they deliver a tested, guaranteed solution.
To begin, you should first determine the level of coordination that suits your specific application and business requirements. Next, you should choose a manufacturer that has ensured that their motor starter complies with coordination standards. This requires testing the combination of components to the associated standard, and accordingly publishing the coordination tables for selection.
As the pioneers in the field of motor control with over 90 years of innovations, Schneider Electric offers the widest range of motor starters and coordination tables. All of these are easily accessible from our product catalogue.
No matter what kind of starting method you need, our online EcoStruxure™ Motor Control Starter Configurator will help you quickly and easily select the optimal combination of components to ensure maximised motor safety, protection, and uptime. Click here to learn more.
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