So, what did we achieve in this year, may be great, may be just about average, or even lesser………

Reminds me of the romantic lyrics of an old “Carpenters” song titled “Only Yesterday” – “Only yesterday when I was sad………….you showed me the way to leave the past……………tomorrow may be even brighter than today”

The best way to convert the new challenges to great opportunities is to meet them head on. We have tightened our belts and lived long enough in the current financial melt down, maintenance budget cuts, energy use optimisation pressures, lack of all types of resources and bleak forecasts about the future. So, what do we do?

• Regular, detailed planning of all activities will always be fruitful in effective and efficient job execution. A few minutes spent in forward planning can save hours of chaotic and stressed operations.
• Always have a Plan B, just in case Plan A doesn’t work out as expected.
• Try and improve on the Plan A compliance percentage.
• Use all possible tools to improve your planning ability.
• Build a team that will stand by you in bad times as well as good times. (A little difficult, but definitely possible)
• Train your team regularly to improve their effectiveness and efficiency.
• Be an exemplary leader

Most of the suggestions given above will not cost you much in terms of money, but can reap wonderful benefits.

“Season’s Greetings, Merry Christmas and best wishes for a Happy New Year to all viewers”

•  Heading back to the stores for parts, consumables and special tools.
• Waiting for support equipment such as platform trucks, boom lifts etc.
• Waiting for the equipment / system to be maintained to be handed over to them to start work. In some cases, “LOTO” may impact more than the specific equipment to be worked on and clearance may not be given for work to commence.
• Waiting for different craftsmen to come and do their planned work.
• Unsafe conditions prevailing in the area to be worked on that needs to be set right before commencing work.
• Being called in to attend to other urgent unplanned work.

Such interruptions cause avoidable delays in completing planned jobs. This could have a snowball effect with large number of planned job accumulating.

So, what do we do? How do we improve the efficacy and efficiency of PM or PdM processes and improve productivity of maintenance personnel?

•  Identify and document all planned jobs that need to be done over a period of time. Detailed planning effort is required.
• Prioritise the work. Follow an analysis akin to VED (Vital Essential Desirable) system.
• Assign the tasks to various technician groups as per craft requirement, shift in which the job is to be done and availability of personnel. This would reduce the ambiguity on “Who” is to do “What” and “When”.
• Develop a work structure and culture such that availability of all resources are ascertained before the work plan is promulgated. Check for stores items availability, special tools availability and condition, qualified technicians and their shift schedule etc.
• Ensure that support equipment such as platform trucks to move heavy stores, boom / scissor lifts to access equipment located at heights are available with authorised / licensed drivers. This may require forward planning and liaisoning with other departments.
• Ensure that resources such as material / special tools required for a job, but not available are procured in time and kept ready for use.
• Assess impact on the total system if work on some equipment or part of a system is planned. Liaise with production / operations group / internal clients to schedule such jobs with a consensus view to reduce the impact on production or total system availability. At times, total shut down of plant / services may also be necessary.
• Re-assign shift duties to get the right people together.
• Safety is of prime importance. Periodic safety audit and risk assessment for each job will help in this aspect. Proactive safety inspection before starting a job will help in avoiding hold up in this regard.
• Structure the work group with a separate team to tackle emergency and break down repair work. This may be tough to achieve with the limited manpower resources. Such a set up would reduce the instances of planned jobs getting sidelined due to emergency work.

Analysis of various reasons given below will also help in correcting the work plans and optimising maintenance efforts:

•  Wrench time spent on planned versus unplanned work.
• Reasons for work being kept on hold.
• Reasons for recurring defects.
• Frequently used repair methods for various defects.
• Frequently reported deficiencies and complaints.
• Equipments / systems that fail regularly.
• Expenditure towards maintenance of various equipment and systems.

With legacy systems such as pen and paper log books, spread sheet records etc, the data availability for ready use is limited.

This is where a good CMMS suite comes in. A system such as MPulse CMMS / EAM has evolved to take in all the good maintenance practices from a large variety of industries and other users. The computerisation makes the data capture easier and the analysis meaningful.

Log on to www.mpulsesoftware.in to get to know more about CMMS / EAM suites.

Having a strong committed core team to build the maintenance system is essential to begin with. A “Top-down” approach in the initial setting up phase followed by a “Contributory” approach after the system matures are likely to get maximum benefits.

Kaycee

]]> http://maintrain.wordpress.com/2011/12/06/fine-tuning-maintenance-effort/feed/ 0 maintrain http://maintrain.wordpress.com/2011/11/18/managing-spare-parts-supply-items-and-tools-in-maintenance-management/ http://maintrain.wordpress.com/2011/11/18/managing-spare-parts-supply-items-and-tools-in-maintenance-management/#comments Fri, 18 Nov 2011 09:29:39 +0000 KC Ajith Kumar http://maintrain.wordpress.com/?p=851 ]]> Every maintenance management set up handle some amount of inventory by way of spares, supplies and tools; this is irrespective of the organisation size. For smaller teams, the inventory management could be a simple task since the quantities and variety would be less. As the size grows, so does the variety and inventory.

The OEM and AMC vendors normally give a set of inventory requirements (at times inflated) as regards maintenance effort. Many of these items go unutilised and we get into a situation where we hold a large inventory including non-moving items.

How do we optimise the inventory holding, thus reducing the overall maintenance cost?

Re-organising an existing store room or starting a new one are both time-taking and requires focused effort. Starting a new store room is comparatively simpler since we are starting from scratch and go by some inventory management logic to begin with. Revamping an existing an store room requires much more effort and thought. We will deal with an existing store house in detail in this post. 

Redundant / Out of Service / Obsolete Machinery, Equipment and Systems

• Over the years of operations, some of the full equipment and machinery or full critical sub assemblies that we had ordered as hot spares might not have been used at all and may languish in the store rooms. Decide on how to dispose them off using the following options (just indicative and not necessarily exhaustive):
• Replace the old operational machinery and equipment with the new ones in store. After a short observation period, dispose the old items at the maximum possible price. Benefits – Lesser inventory level, new set of operational equipment / machinery with that much more reliability & life, scrap sales income accrued.
• Replace the existing sub-assemblies with new ones from the store. After these stabilise in operation, dispose the old ones at the maximum possible price. Benefits – Lesser inventory levels, new set of sub-assemblies in operation prolonging the equipment  life, improving reliability scrap sales income accrued.
  
• Get the OEM to buy the items back at the best possible price. Benefits – Ideal way of waste reduction and reducing the inventory cost.
• In case it is strongly felt that we need to keep a hot spare that can reach the site in a short time, get the OEM or AMC vendor to take back and hold the full equipment or critical sub-assembly in their stock. Some hard bargaining may be essential. The population of similar equipment or critical sub-assemblies in your geographical area of operations (not necessarily with you) may clinch the issue in your favour.
  
• We may have replaced a few of the equipment / machinery / systems over the years with more efficient or better ones. The older full items, spare parts and special tools (if any) would still be part of the inventory. What do we do in this scenario?
• Dispose the full items at the best possible price.
• Inspect condition of spare parts and other supplied items,  check for spares and supply items compatibility with other operational equipment (for example, bearings, seal units, couplings, fasteners, electrical contacts, switchgear, oils, greases etc) and dispose the unusable parts and supply items at the best possible price. Check with OEM for buy back.
• Inspect all the special tools, check for compatibility and useability on operational equipment and dispose the unusable items at the best possible price. Check with OEM for buy back.
• When equipment / machinery / systems are being replaced, negotiate a buy back of the items being replaced with all the spares and tools with the new supplier.
  
• With the rapid technology advancement, obsolescence has become a major problem, particularly in the electronic and microprocessor control units. We could get into an agreement with the OEMs to regularly upgrade the obsolete units with new ones with a buy back agreement of the old ones with all the spares.

After getting rid of all the useless inventory, now let us focus on optimising the useful inventory.

Optimising Current Useful Inventory

Assuming that we are using a CMMS Suite with an Inventory module, firstly there need to be a list of all assets under our maintenance. The inventory needs to be divided into three broad categories, namely:

• Spares – Made up of full equipment / sub assemblies held for “Hot swap”, and other spare parts.
• Supply items – General items of stores such as oils, greases, gases, cleaning material, standard rubber hoses, adhesives (general and specialised), sealant material etc
• Tools – This can cover general day to day use hand tools, special jigs & fixtures, equipment specific special tools such as Injector removal spanners, bearing pullers etc. Specific PPEs also could be listed under this category.
  

A screen shot of MPulse CMMS indicating the categories and the fields required to be filled for identifying an inventory in the “General Tab” is given below for easy understanding.

Linking of inventory items that could fall into the above mentioned three categories to each equipment would help in sharing the inventory resources over a larger number of equipment.

For example, Diesel Engines used as Generating set prime movers, emergency fire pump prime movers and air compressor prime movers may all use SAE 40 oil in them. The quantity of oil to be used in each would be specified by their respective OEM. By clubbing together all the requirements together, we can optimise the onsite stock of this oil. A screen shot of this feature in MPulse CMMs is given below:

On similar lines, the reverse process of linking each equipment asset to inventories also can be done.

As the operations get mature, the actual inventory usage need to be reviewed and the changed actual figures are to be incorporated into the CMMS data base. For example, Genset suppliers specify renewing engine oil, air filter and lub oil filters as part of 250 hrly maintenance.You may realise over a period that in your current operating environment, the 250 hrly changing of air filters is not required, but could be prolonged to 750 hrs with cleaning of filters with LP air being done every 250 hrs. This will reduce the maintenance expense and eventually, reduction in inventory.

Maintenance technicians appreciate a “Bill of material (BOM)” approach in Work orders. While scheduling planned maintenance and making work orders for break down repair work, a BOM will make it that bit easier for the technicians since they approach the work spot with all the essential spares, supplies and tools, thus reducing time wasted in going back to the stores for items frequently. Good CMMs systems will have a feature to link Scheduled Work, Work orders and Work Instructions to required inventory. A sample screen shot from MPulse for a scheduled work is given below:

A good maintenance related inventory module will reduce the time taken by assigned technicians to search for all the required material, get them together and do the job. Some systems even will allow the worker to raise a requisition for all the material they need. 

Common and general hand tools or special tools could be linked to and issued to individual technicians. This will help in tracking “Who holds what, where” and sharing the available tools optimally.

An additional benefit is derived when an equipment in the facility is being removed from service. The parts
associated with that equipment are quickly identified so that they can be removed from the storeroom as well.

That is all hunky dory. Why is it that many organisations operating with with good CMMS suites do not use the inventory modules fully?

• Firstly it needs initial planning to set up the inventory list with all details in an electronic format.
• Secondly this needs to be imported into the CMMS suite.
• Thirdly, the items need to be linked to individual assets (equipment , machinery, systems)
• Fourthly, the data needs to be updated whenever there is usage and replacements.
• Fifthly there needs to be a person motivated enough to understand the store philosophy, maintenance philosophy and understanding the economics of maintenance cost to drive the project. 

Hope that I have been able to stir up some interest in the inventory management in some of you readers. I will cover the subject further in later posts.

A top priority for every maintenance and engineering manager is to protect building occupants, workers and visitors. But managers too often forget the people who work behind the scenes and perform the most dangerous tasks in the said environment — the front-line maintenance personnel, more so the engineering technicians.

It is said that, annually, the Occupational Safety and Health Administration (OSHA) issues about 40,000 citations in USA. To avoid injury to maintenance personnel, as well as citations and fines, we must develop a plan for worker safety that complies with OSHA or any other local safety body and create a healthier environment for the maintenance staff.

Repeat Offenses

10 most common violations of the safety code are covered below. While we emphasise safety during training sessions and supervising the maintenance staff, departments still commit many common violations related to:

• Use of Personal Protective Equipment (PPE). Training of personnel in use of PPE related to their individual deployment is as important as enforcing their use. It should become a part of their psyche to use all the prescribed PPE in every job they do.
• Electrical hazards. Awareness of general conditions is a must for every individual. Detailed instructions are to be given to the personnel actually working in areas with electrical hazard.
• Machine guarding. As a rule, all machines come with suitable safety guards; these get misplaced or damaged over the years and slowly vanish from the place. Regular audits of machine guards availability is a must and personnel in charge of equipment, machinery and systems should be held responsible for the safety aspects on the items allocated to them.
• Hazard communication. This is a very weak link. Everyone should be trained and encouraged to report hazards that they find in the place of work or otherwise, irrespective of its severity.
• Misuse of flexible, extension chords. Very commonly seen violations are: Usage of chords without proper plug tops, lack of earthing, non provision of ELCB, unsafe joints in the cable, overloading etc.
• Fall protection. On many occasions we see personnel wearing the fall protection with the arresting chord wound around their torso. In other cases, the fall protection chords are not anchored properly.
• Lock Out and Tag Out (LOTO) on energized equipment and systems. Safety of personnel working on downstream equipment and system elements is paramount. A well established LOTO will help in avoiding mishaps due to personnel unknowingly energising electrical circuits on which work is in progress or starting machinery being repaired. 
  
• Inaccessible portable fire extinguishers. On many occasions, portable fire extinguishers provided with good intentions are found to be obstructed from view or even totally inaccessible. This would defeat the very purpose for which it has been provided in the first place.
• Welding and hot work. Proper inspection of the hot work site and peripheral areas are at many times overlooked. Barricading the work area is a good idea. Issuing hot work clearance certificates involving all the affected groups, including security personnel would reduce the probability of an accident and help in emergency reactions.
  
• Compressed gas cylinder stowage and handling. Compressed gas cylinders need to stowed and handled properly to avoid mishaps.
• “Near miss” reporting. Many times an actual accident may not have occurred, but a “Near miss” would have. People are diffident in reporting such events for the fear of repercussions and lengthy administrative inquiry / hazard analysis. “Near miss” reports can help in avoiding recurrence through process or activity changes or making physical changes to an area as the case may be.
• Documented training records. Though not directly affecting safety, these records would help in understanding training needs, planning training sessions and documenting training outcome. Record keeping is at times perceived as an administrative chore, hence neglected.

Depending on the scope of a department’s activities, each of these issues can endanger maintenance personnel and operations. We must ensure these common violations do not hamper the department’s efforts to create a safe, efficient and effective work environment.

Adapted from an article by David Casavant in Plant Engineering Issue

Learning to identify and avoid the recurring traps in your maintenance program will help you to be more effective in the application of both preventative and predictive maintenance techniques.

Pitfall #1: Capital Expenditure for equipment, but not for training

When maintenance budgets are submitted, and ultimately cut down, many companies fail to provide funds for adequate training to support the new Predictive maintenance related equipment. For example, some organisations invest on expensive infrared thermography equipment, but do not provide funds for proper training of personnel to exploit the full potential of the equipment. Thus the equipment would remain as an expensive toy with very little return on investment.

While OEM training on the basic operations and capabilities of the supplied equipment is essential, investment in the right kind of training is critical. OEM vendors may provide basic how-to-use training, but this may be inadequate for the users to utilise all the possible features and further more. Training by a brand-neutral or independent trainer for a particular technique using the new equipment would be beneficial on the long run. Training more than one person is also recommended to ensure year round availability of specialists. A word of caution – Do not train and allow too many people to handle expensive equipment since accountability for
equipment faults, damage etc becomes less.

Pitfall #2: Applying one predictive technique for all situations

If the only tool you have is a spanner, then every problem looks like a bolt. For instance, if you only have a vibration analyser, would you be able to identify loose connections in an electrical enclosure? Understanding the proper application of the different predictive tools is paramount to implementing and sustaining your system. Most predictive techniques are used together to improve reliability, aid in root cause analysis and improve safety. Organizations have obtained good results using a combination of predictive techniques like contact ultrasound, vibration analysis, oil analysis and thermography on gearboxes. They have been able to cut repair costs significantly by identifying a failing component instead of replacing an entire assembly.

Pitfall #3: Failing to properly re-inspect after corrective work is complete

The above scenario occurs all too often, in far too many operations. Predictive maintenance identifies problems that usually are undetectable by human senses. If the problem could only be seen with the predictive equipment, then the same reasoning should be applied when re-inspecting it. There are many instances where a repair has left the equipment in worse condition than before. For example, corrosion develops inside an electrical connection and maintenance makes the situation worse by tightening the connection. Or, in disassembling piping to repair an air leak, mistakes are made when putting the piping back together.

Without proper re-inspection, we would have no idea of the havoc we have caused in our own system. When you are using predictive techniques to identify a problem, ensure that your system schedules a re-inspection using the same technique.

Pitfall #4: Predictive Maintenance Corrective work orders get lower priority

Organisations that haven’t made the transition from reactive or breakdown maintenance to preventive maintenance will not be very effective in adding predictive maintenance to their work strategy. Maintenance supervisors will tend to prioritize more obvious problems.

All personnel involved in the maintenance process, especially those that have been working in a “reactive” maintenance mode need to understand that predictive work orders are a priority.

Predictive maintenance replaces parts before they fail—and this is a mindset that only comes with training and practice. The savings can be tremendous when parts are replaced before catastrophic failures take place to full machine assemblies.

Pitfall #5: Lack of a supporting maintenance system

While many companies will spend enormous amounts of time and money on tools, equipment, parts and materials, they will not focus on developing the foundation of a good maintenance organisation—the maintenance system. Using predictive techniques without an effective maintenance system in place only optimizes your reactive maintenance program. It will result in marginal savings and less-than-anticipated payback. Predictive maintenance is good, but you must have the other programs in place to support it.

Watch your step

In summary, recognising and avoiding the above mentioned five pitfalls of Predictive maintenance adds substantial value to any maintenance organisation.

Adapted from an article by Mark Pond of Marshall Institute – Posted by Maintenance Technology

Any flooring type that is cleaned and maintained properly will meet or exceed users’ expectations. But with the tight maintenance budgets, pressure is mounting to minimise floor maintenance by cutting cleaning frequencies. Reduced cleaning frequencies will mean greater wear and tear on the floor.

To extend the life of flooring, we need to implement the essential elements of a comprehensive flooring maintenance programme. Among the critical factors to consider:

• Flooring maintenance tasks. Regular vacuuming is critical for carpets because the faster housekeeping crews remove dirt, the less damage it will do and the longer carpets will last.
• For hard flooring, such as vinyl composite tile or terrazzo, regular dust mopping and damp mopping remove grit before it can damage the floor’s gloss.

• Task frequency. With tight budgets, it is common to hear that flooring maintenance tasks are not performed as often as before. Offices that had been cleaned daily now are cleaned on alternate days, or even weekly or monthly. No matter the type of floors in these offices, their surfaces will be damaged faster with less-frequent cleaning.

• The time to perform tasks. With budgets tightening, employees inevitably must do more with fewer resources, including time. But housekeeping crews must have enough time to perform proper flooring maintenance. Ironically, there is a law of diminishing returns from cutting maintenance time. Floors that are cleaned daily take less time to clean on average than floors that otherwise might be cleaned only monthly.

• Proper training. Since facilities often feature many different floor types, crews need comprehensive training on flooring maintenance. It is easy to omit this step from the program, but failing to train workers in the proper use of floor-cleaning chemicals or equipment can result in damaged floors. Floor maintenance training should include a review of proper chemical use, equipment considerations, and appropriate cleaning frequencies and safety procedures.

A good flooring maintenance program must also take into consideration the following conditions:

• Traffic. How many people walk across the floor, and what is rolled or dragged across it? One may get high traffic areas within large spaces. Such places will require more frequent care.
• Environment. What type of soil is left on the floor? Seasonal changes also may be taken into consideration in view of the higher probability of dirt being carried in with moisture.
• Congestion. What physical obstacles hinder flooring maintenance procedures? Periodic inspection of office and other spaces to remove unwanted stuff would help in decongestion.
• Time. When can workers perform floor-care tasks? Shift timings, meal timings, weekly holidays etc could be considered.
• Size. What is the square footage of the area to be maintained? Staff strength, skills composition, equipment and tools requirement etc will come into play in the decisions.

With this information, we can develop and implement a comprehensive flooring maintenance program to ensure floors consistently look their best.

Are the employees really serious about safety?
Is it fostering the most cost-effective culture? Are we doing your part?

Organisational responsibility for safety might formally be assigned to a specific department or a group of safety experts, but effective implementation involves everybody and depends heavily on engineering and maintenance. Nothing gets done in a facility that’s not installed and maintained properly. When there’s a safety problem, they need to get to it and do essential rectification.

Maintenance personnel stand more risk of accident and/or injury than other employees in view of the nature
of their job requiring specialised skills and at times work done in remote, difficult to access areas. They also are sometimes forced to work alone due to lack of access space in the work spot.

Safe Returns

If safety was free and easy, everyone would be safe. But building and maintaining a safety culture takes time, effort and money. A company might go for a long time without a loss or safety incident and may not realise the risk. The cost of an accident can ruin a small company, and so can the consequential loss of knowledge and expertise. The cost of the injury itself (worker compensation and medical expenses) might be dwarfed by cost of lost production.

An arc flash may or may not kill, but equipment could get damaged and production lines may stop. With multiple accidents, the insurance coverage cost also would increase, in view of higher risk rating by insurance firms. It is cited that, as a result of improved safety, Schneider Electric’s North American Operating Division saw its medical incident rate drop 40% in 2006 at its North American manufacturing facilities. This translated to a savings of approximately $2 million, split between workers’ compensation and indirect costs.

It’s impossible to guarantee that investing in safety will prevent all incidents, but not investing in safety will result in increased probability of incidents occurring, either on or off the job. Avoiding the cost of a single incident that would have injured or killed an employee can pay for a safety training program for a group of employees.

Safety is a Culture

The specific regulations, staffing, equipment and training that is essential to maintain a safe working environment depend on the nature of the operations. The critical element is fostering a mindset that truly gives safety more than lip service.  Like maintenance, some see it as proactive versus reactive. Like any initiative, safety must be driven from the top.

As a company’s number-one priority, it must be discussed first at every meeting, tracked with key performance indicators (KPIs), and part of every manager’s performance review.

As a complex combination of knowledge, observation, attitude and action, safety depends on day-to-day interaction of everyone in the plant. Goals, resources and systems depend on leadership and management. Workers who are most at risk have to feel that commitment from the top – that they can raise a safety issue with their supervisor.

Suggestion systems help the management see ways to improve safety. Maintenance and engineering are often
the critical links between recognising a hazardous situation and implementing a solution. Their talents are also critical on the safety committee, and as part of any incident investigation.

Behavior makes the difference

Walking through a facility can give some idea of a company’s safety competence, and employee behavior reveals the rest of the story. Every company has a safety culture, good or bad. Those companies that truly excel have a culture of safety where each person believes in safety, not just complies, and takes personal responsibility for their own safety as well as the safety of those around them.

A safety-minded company will conduct a thorough incident investigation and try to analyse the information from
any safety mishap, even a “Near miss” event, reevaluate the process and make the necessary changes or
corrections to ensure that such incidents do not recur. A less-safety-minded company may not take the time
to investigate, just because there was no injury. Just because no one got hurt in this particular incident does
not mean that the outcome will be as favourable the next time about.

How to get safer

The two most often repeated keys: The drive to safety must come from the top, and it must become everyone’s
core value. Du Pont Inc follows a concept of “Felt Leadership” that indicates the visible management commitment and passion for safety. Some of the attributes are listed below:

Felt Leadership:

· Is easily observable
· Clearly demonstrates belief in safety
· Makes a positive impression on employees
· Demonstrates a personal commitment
· Pervades the whole organisation
· Affects all employees positively
· Involves all employees

The principles of Felt Leadership include:

· Be visible to the organisation
· Recognise one’s role as teacher/trainer
· Develop own safety functioning skills and pass them along to the organisation
· Behave and lead as you desire others to do
· Confirm and re-confirm safety as the number-one value
· Place continuous emphasis and clarity around safety expectations
· Show a passion for zero injuries, illnesses and incidents
· Celebrate and recognise “zero” successes

Every employee has critical responsibilities to a safety culture:

Finance: Understand and publicise the business value of good safety performance.
HR: Develop guidelines that embody good safety performance and leadership as performance indicators used in promotion and pay increase considerations each year.
Supervision: Uphold full responsibility for the safety of every individual working in their crew and ensure that each and every employee receives the necessary training to perform their jobs safely.
Technicians and operators: Maintain individual responsibilities to respect safety procedures and make sure their fellow workers also are adhering.

Safety is worth the trouble. It’s not just about the company and the bottom line. When each person goes home to their family alive and intact, it keeps families together. Think about that.

Person A (Org A) 17 Feb 01 22:55

I need to know if it is possible to run a 180KVA DG set in parallel with a 500KVA DG set (Synchronising). If yes, what are the precautions to be taken for safe operations?

Person B (Org B) 18 Feb 01 21:55

If properly engineered and designed, one may run the above DG sets in parallel. They have to be properly:

1. System grounded (system ungrounded is possible but to be avoided, if possible)
2. Individually protected
3. The downstream power distribution must withstand their total short-circuit fault currents and short-circuit MVAs.
4. Designed for the same frequency
5. Avoid a short intermittent on-off duty of one of them to keep system stable.
6. Loaded according to their permissible loading, kVA vs time curves.

Person C (Org B) 19 Feb 01 9:15

In addition to the general factors mentioned by Person B, you need the following specifics:

1. The governors must be set up for parallel running. This usually means that they must be set for the same percentage droop, so that they can share load in proportion to their ratings. Other control options are available, depending on the type of governor in use.
2. The voltage regulators must also be set up to share reactive load in proportion to rating. This will usually also mean load droop control, or cross-current compensation between the two AVRs.
3. Of course, you will need synchronizing instrumentation & controls to parallel the units in the first place. This can be automatic or manual & can be simple or complex depending on your requirements.

Person A (Org A) 19 Feb 01 14:23

Thanks to Person A and Person B for their helpful hints. The system where I am going to implement this is already running 3 sets of 500 KVA in parallel. The neutral (star point) of each alternator is connected to ground through an isolating contactor, only one of which is on at a time (the rest being floating). The latest set of 180 KVA is being added to take care of peak
load requirements.

The paralleling instruments already in place are : Synchroscope (rotating LED type), Check Synchronising Relay (SKE11 Electro-mechanical) and also the dark lamp method!

The other protections are Reverse Power Relay (CCUM21) and Earth Fault Relay (CAG14) for each DG set. Each Alternator is protected by motorised air circuit breakers.

I was wondering if you know any reference book on this subject of synchronising of DG sets.

Person C (Org B) 19 Feb 01 15:10

As far as references are concerned, I suggest that you try the appropriate manufacturer websites. Basler and Woodward governor would be good starting points.

Person B (Org B) 25 Feb 01 16:26

Suggestions:

1. I had to keep my answers in general to avoid any unrelated specifics such as the power management, loading percentages, etc.
2. The original posting calls for safe operation of the additional 180 KVA DG. The power management strategies are considered on safe side.
3. More info on DG units and their controls is available over manufacturers such as http://www.thomasregister.com

•   Type Governor under Product / Service that will return Governors: Diesel Engines and 2 companies in addition to the mentioned ones in the previous posting.
•  Type Generator Product / Service that will return Generator Sets: Diesel Electric 181 Companies for good selections on more info

4.   References:

• Bergen A. R. “Power System Analysis,” Prentice-Hall, Inc., 1986 Page 390 Section 12.5
• Special Case: Two Generator Units describes in more detail “power control of two generating units,” including frequency droop characteristics

Person A (Org A) 27 Feb 01 10:56

Even as we were corresponding thru Eng-Tips,I was carrying out the installation work (cabling, control wiring etc.)at the site. Yesterday, I commissioned the set (180 KVA, 415V, 3 phase) by synchronizing it with the existing 3 x 500 KVA sets. I am glad to report that the set ran for over 4 hours in a synchronised state without ever tripping. As the load sharing is being done manually, I tried to load the 180 KVA set but could raise it to only to 90 KW. At this loading, it was drawing a current of 200 Amps. This ampere load remained fairly constant even as I decreased the KW load even to 20kW ! I am still scratching my head over that !

I have asked for the governor to be calibrated afresh ( mainly to give me time to think of a viable load sharing scheme ! ) Well, thanks to Person A & Person B for their interest and without whose prompt replies, I would be still groping in the dark.

Person C (Org B) 27 Feb 01 12:35

Glad to hear that you were successful in commissioning the set. A couple of thoughts regarding your results:

- At 90 kW, 200A, 415V you were operating at 144 kVA and a power factor of 0.63; reducing the real power to 20 kW, you kept at 200A with a power factor of 0.14. How is the control mode of AVR set up?
- You may want to try reducing the excitation to increase the power factor up to the rated value (0.80? 0.85?) for this loading. How did the bus voltage respond when the unit came on-line? It should have increased noticeably, so that reducing the unit excitation would bring it back towards nominal.
- Assuming that you are not connected to the grid, you may have to back load off of one of the other running sets to get the 180 kVA unit to pick up more load – it all depends on the droop settings. What control mode is the governor set up for? You may also want to verify that the prime mover isn’t limiting the output due to some mechanical problem.

Person B (Org B) 27 Feb 01 13:31

Suggestions:

1. Power flow simulation by suitable software performing power flow analysis/management could help.
2. 180 kVA generator is supplying power to the parallel generators. Please, notice that various regulators, controllers, governors, etc. have their boundary conditions and operating regions. If the current setup does not fit the limiting conditions, there may be a need for their customizations.

Person B (Org B) 5 Mar 01 18:42

Suggestion – Visit:

1. http://www.dynex.com/fyi3.htm
2. http://www.egsa.org/powerline/past/mj99plantbas.htm

For more info, and help, contact:

Selco USA, Inc. for Load Sharer T4300 for application diagram at 770-455-9110 (Atlanta, GA, USA) or email SELCOUSA@worldnet.att.net

That is the end of the extract. Hope that this chat extract was of assistance to you, or at least opened your thought process on the synchronising and paralleling of DG sets.

For example, since nearly every electrical component heats up before it fails, infrared inspection as a diagnostic method can provide a cost-effective method for identifying potential problems in electrical systems before damage occurs and safety hazards arise. If we find potential problems early enough, remedial measures can be planned and scheduled to our convenience, thus eliminating unplanned production / services downtime.

Infra red imaging thus helps in setting up a condition based maintenance system. Corrective measures could be taken depending on the severity of the identified condition.

New-generation Equipment

Unlike the fragile, bulky, and expensive first and second generation IR imaging equipment, the new-generation equipment is more compact and durable. With the reduction in cost of equipment, it is now possible to get fairly good IR Imaging cameras for about USD 5000.

Of the latest advances in infrared thermal imagery, a few  manufacturers have developed technology that integrates infrared and visual — or visible light — images in full screen or picture-in-picture views. The technology helps users recognize image details and better identify problem areas by quickly scrolling through the different viewing modes. They include:

• Full infrared — high-resolution, standard infrared images
• Full visible light — a visible-light image similar to that of a digital camera reference
• Automatic blending — combines infrared and visible-light images blended at user-adjustable levels for maximum image clarity
• Infrared/visible alarm — displays only the portions of the image that fall above, below, or between a user-specified temperature range as infrared, leaving the remainder of the image as full, visible light.

A huge advantage to this application of thermal-imaging technology is that we can perform scanning while the system is live, with no impact on the facility or its operations.

Safe Infrared Scanning of Electrical Panels Starts with Personal Protective Equipment

We can safely scan electrical equipment with a thermal imaging camera in two ways: by leaving the panel closed and scanning through a specialised infrared window or by opening the electrical panel while wearing all of the required personal protective equipment (PPE).

Depending on the arc-flash rating of the equipment, PPE could include but is not limited to protective clothing, gloves, and a face shield. Most arc-flash events happen because of a change in state of the equipment, such as opening a piece of equipment to scan it.

By installing infrared windows, technicians can scan electrical equipment more frequently and safely, as well as without being forced to change the state of the equipment.

Other Thermal Imaging Applications

The thermal imaging applications go beyond electrical systems and cover a few more such as:

• Scan the exteriors of commercial buildings for heat leaks. The thermal imaging equipment allow them to identify places where heat is escaping through the shell or windows or doors.
• Thermal imaging of internal combustion engines help in identifying the health of individual cylinders through comparison of temperatures at the fuel ignition point and the running temperature of each cylinder.
• Many international airports have installed thermal-imaging cameras during the recent H1N1 flu outbreak to help identify travelers with elevated body temperatures as a first-level defense against the virus infected people entering.
• Firefighters use the units to see through smoke and detect trapped people, as well as to locate the base of a fire.
• Law-enforcement officials use them to track down suspects and find missing persons.
• Medical applications are expanding, since inflammation and the resulting increased temperatures accompany many diseases in the human body.

Adapted from a series of articles By Michael Newbury in PE Edition of March 2010

• A work orders have to be made for emergency repair work, planned jobs and preventive maintenance jobs
• For planned jobs, priorities have to be defined
• Work orders have to be prepared (materials, number of hours, crafts and tools)
• When the number of hours are known per work order, the workload becomes visible
• When priorities are defined, it is easier to plan and optimise the resources.
• When work orders are executed, the real hours and comments have to be entered, so that the history of executed work orders becomes a working instrument.
• An easy system must be in place to manage the above principles.

These principles are simple and easy to execute. There is no need to wait for highly priced or sophisticated computer programmes to monitor the work. Simple word processor documents or spreadsheets can be used to make good formats and records. At this point, these records may not allow deep analysis of failure patterns, expenditure on each job etc.

As the maintenance crew gains experience and confidence in the operations, upgrade and start using good CMMS / EAM systems that would give more flexibility to maintenance planning. There would be improvement in both efficiency and effectiveness of maintenance. On the long run, there will be cost reductions by way of better labour productivity, reduced inventory costs, enhanced equipment life, increased system reliability and optimised maintenance effort. Finally, the OEE also will improve since mathematical values of all the three components would be higher.

Kaycee