Preventative maintenance for MCCs
Preventative maintenance prolongs motor control centre lifespan
The Beverly Clock has not been manually wound in more than 150 years, but its clever mechanism keeps it ticking with minimal problems. In spite of this, the clock has stopped working on a number of occasions. However by cleaning, maintenance and environmental changes the clock has been kept in operation. To keep a Motor Control Centre (MCC) running, it’s important that maintenance is done proactively to prevent costly downtime. Here, Pat McLaughlin, operations director of Boulting Technology, explains why preventative maintenance is so important for MCCs.
MCCs are often at the heart of a manufacturing plant, providing power for equipment across the site. However, their important role often goes unrecognised – for a long time there has been a ‘buy and forget’ attitude to MCCs. It is a common belief that once an MCC is installed, it can be left to run independently and maintenance is only needed in the case of a breakdown.
The problem with this approach is that an MCC fault, such as a starter failure, can lead to major downtime by causing loss of power to, or control of, plant equipment. The consequences of interruption to production can mean significant financial losses to a business. Even worse, if documentation is not kept up to date or spare parts are missing, there can be a considerable delay getting processes back up and running.
If the MCC is neglected for an extensive period of time, this can lead to a risk of catastrophic failure, which leaves companies not only with downtime, but also with a hefty investment to replace the equipment.
When purchasing a new MCC, the manufacturer will specify the life expectancy, or expected obsolescence, of the equipment. All MCCs have a finite lifetime, but not all of them meet initial expectations. Typically the life expectancy is around 20 years, but in some of the worst cases where components have failed in less than two years; this is usually when a fundamental lack of maintenance and other significant factors such as a very harsh environment has dramatically reduced its life. Preventative maintenance is a key tool to ensure that the MCC’s life expectancy is upheld.
In order to prolong the life of the MCC and limit the risk of breakdown, companies can enforce a Planned Preventative Maintenance (PPM) regime that involves proactive maintenance activities typically every three to six months. Incorporating a structured maintenance regime means that potential issues can be corrected before major downtime and ensures regulatory compliance.
If an MCC is produced in Europe, it will be manufactured in accordance with EN61439 — the standard that defines specific requirements for switchgear and control gear assemblies. If it is later modified, there is a risk that the MCC may no longer comply with this standard. When maintenance involves replacing or changing components, companies need to be mindful of the regulations. Maintenance staff should check for any modifications, and ensure that documentation is up to date.
A new MCC will come with an Operation and Maintenance (O&M) manual with clear instructions on what procedures should be put in place and how to keep the MCC healthy and in-line with regulations. Companies can use this to plan preventative maintenance, ensuring that all important components are checked.
Assessing the situation
To find out the condition of the MCC, maintenance staff can conduct several checks. These can be intrusive or non-intrusive, from simple visual checks to more complex analysis.
It is important to make checks to establish the cleanliness, verify any software and check and backup the parameters on programmable devices. These parameters need to be up-to-date with records. Maintenance staff can make visual checks to look for any discolouration or burnt out equipment.
As MCCs are often tucked away, there is also a danger that vermin can be present. This can cause serious problems with cables or connectors becoming damaged or even destroyed. Maintenance staff should conduct regular checks on the physical condition of cabling. If problems are identified, steps can be taken to restore the MCC to a good condition. If problems are recurring, it is important to remove the root cause.
Restoring the MCC to how it should be is similar to taking a car in for a service.
Common maintenance activity includes cleaning and tidying equipment, cleaning air filtration systems and fans to reduce overheating and replacing the batteries of backup systems.
When a breakdown happens, it is common for maintenance to use a quick fix to get production going as quickly as possible. If previous maintenance has been done for a quick fix, this needs to be resolved by restoring everything to the manufacturer’s specification.
The aim of this maintenance is to restore the MCC to its original condition. If any components show wear and tear, these can be serviced or replaced. If there is a problem with the MCC, companies can then perform the required maintenance.
Health and Safety
MCCs generally present very few health and safety hazards, except when performing maintenance activities. It is vital that companies and their employees are aware of the hazards and take sufficient precautions to manage them. Before working on MCCs, maintenance staff should test the equipment to see if it is ‘dead’, follow correct procedures in the O&M manual and wear correct personal protective equipment (PPE). A risk assessment and method statement should be produced for each maintenance activity.
Smart controls on the MCC can be incorporated into preventative maintenance regimes by logging, informing and indicating the operator of important information. The operator can interpret this information to gauge how well the rest of the plant is performing, allowing for predictive maintenance across the rest of the facility. Therefore an intelligent MCC can be used to flag up instantaneous problems in other parts of the plant, for example if a fan motor is pulling an unusually high current. This allows the operator to investigate and correct the problem before it leads to a larger failure.
Intelligent systems can also store data over a number of days or weeks, meaning trends can be formed and any abnormalities identified well before they cause an issue. This allows more focused PPM regimes to be adopted. It also allows for feedback of results of maintenance activities in that trends should return to normal once they have been completed.
Planned, periodic inspections, simple visual checks and an up-to-date record of all maintenance and modifications are imperative for MCCs. To take things a step further, companies can use intelligent devices to predict where maintenance is required elsewhere in the plant. Proactive maintenance is key to MCCs meeting the manufacturer’s life expectancy. By ironing out any faults MCCs can run just like the Beverly Clock, which keeps on ticking.