Measure, analyse, report, solve

Measure, analyse, report, solve

Measuring your  usage to diagnose where to make energy savings

According to the Carbon Trust, cash savings of up to 20 per cent can be achieved through energy efficiency measures such as installing variable-speed drives (VSD) for fans, pumps, and other motor driven systems. But, a one size fits all approach to energy savings just won’t do. Here, John Mitchell, global sales & marketing director at supply, installation and repair specialist CP Automation, explains how plants should measure their energy usage to find the best energy saving opportunities.

The ISO 50001 standard requires organisations to establish, implement, maintain and improve an energy management system. To make energy savings, a plant manager must first understand their facility’s energy usage. It sounds obvious, but in reality, achieving energy control and crucial ongoing energy savings requires a strategized approach. The first step is to measure your energy usage.

Many modern distribution and energy management systems already incorporate energy monitoring and logging facilities. However, they may only have a limited amount of memory and are unable to store results over an extended period. In addition, many integrated monitors only store summarised data that do not provide the level of detail needed for effective energy optimisation.

Portable power and energy loggers (PELs) provide a convenient and cost-effective alternative, with far superior capabilities. These PELs, from Chauvin Arnoux for example, can be installed in several different locations, with data from different processes or equipment available on a single screen. A real benefit of these modern devices is that equipment doesn’t need to be turned off and isolated during the installation process.

The next step is carrying out an energy audit. The data from the PEL will show where the most energy is being used in your plant and consequently where the most potential for energy savings can be found. The results from this report will inform the type of improvements to implement and crucially where they should be implemented.

Energy saving opportunities can fall into two broad categories, those that relate to the workplace environment and technical aspects of the electricity supply. For example, a plant could improve the efficiency of the workplace environment by cutting down on unnecessary out-of-hours usage by switching to LED lighting with occupancy sensors. On the other hand, an energy audit may find that a motor is consuming a high amount of wattless or useless power. In this instance, power factor correction would need to be installed to reduce this wastage, without compromising the performance of the equipment.

It’s one thing implementing energy savings, but it’s also important to continually monitor your system to ensure you’re getting ongoing energy improvements. Plants should also formulate a metering plan to measure and analyse energy usage over an extended period of time. This will assess whether the chosen energy efficiency measures have been effective or whether further improvements can be made.

Plants may choose to implement energy efficiency schemes for a range of reasons. While there are several universal energy saving fixes, it’s important that facilities use a targeted approach, which accurately monitors their systems to achieve the most effective energy and cost saving potential.

CP Automation offer a range of products and services to monitor power quality problems and energy usage. Visit www.cpaltd.net for further information about Chauvin Arnoux’s industry leading PEL kits which are available for purchase or hire. Alternatively contact sales@cpaltd.net to take advantage of the full data analysis, reporting and  solution implementation service.

 

Case study: Resistor choppers slow overspeeding fans

Fans don’t normally need a braking resistor and chopper but when they are operating in a closed system, a situation may arise where one fan will over-speed the next and the DC bus voltage on their motor drives will then rise. Here John Mitchell of CP Automation, reports on the case of GA Pet Food Partners in Leyland, Lancashire.

External dynamic braking choppers are useful to drive manufacturers, panel builders and end users alike. A seventh IGBT (Isolated-Gate Bipolar Transistor) for the chopper in a six-pulse drive is one way drive manufacturers can reduce the cost of the product by rating the IGBT to a given torque and duty level. Some six-pulse off-the-shelf AC drives manufactured today have a seventh IGBT built in as standard.

The calculation for sizing the internal brake chopper is not a difficult one, but getting accurate data in the first place can be. Some brake choppers on board a drive range from 25% to 100% ratings. And let’s not forget the fact that not all drive manufacturers fit a seventh IGBT above ratings of 22kW.

To this end, where it is too expensive to change the installed drive or where regenerative energy has been overlooked, CP Automation offers a range of external brake choppers that covers 99% of application needs up to 360kW peak, 100kW continuous.

Available in nine models across three frame sizes, there are several options to set the threshold to the desired switching level, along with fault output and master-slave options to chop higher power levels.

External brake chopper units should allow for a fit and forget procedure. During emergency stops the unit will still function – because it is powered by the DC bus and not by an external supply. These were key features for a fan application at GA Pet Food Partners.

GA Pet Food Partners works with some of the biggest pet food businesses in the world. However, it doesn’t manufacture an own label product because it doesn’t believe in having an own brand. It sees itself as a partner, not a competitor, to its customers.

From concept to launch and storage to dispatch, the company claims it partners with more private label pet food brands than any other pet food manufacturer, making it easy and profitable for pet food brands to launch and grow their business.

GA Pet Food Partners operates an environmental extraction system comprised of three parallel 185kW ABB Motors spinning the Halifax fans cascading into smaller fans, and was encountering difficulty in decelerating the biggest of these units. The effect of over-speeding becomes cumulative the more fans there are in close proximity on a factory floor.

The three large fans are controlled by Allen Bradley Powerflex 753 variable speed drives (VSDs) from Rockwell Automation, which count among their features predictive diagnostics to extend the life of cooling fans.

“In an environmental extraction system, if a fan runs too fast, it either pressurises air too much at one end or creates suction at the other,” explained Jayne Whittaker, engineering director at GA Pet Food Partners.

“Some machines on the shop floor have exhaust fans, which need to run at the appropriate speed. CP Automation supplied external brake resistors and retrofitted brake choppers within the existing panels that house the Allen Bradley drives.”

Advanced extrusion

The new GA Pet Food Partners factory is home to the most technically advanced extrusion plant in the world, making some of the finest super premium dry pet foods. GA Pet Food Partners has invested in the world’s first thermal twin extruder, which allows it to include very high levels of fresh meat in premium dry pet foods without the use of dry meat meals.

With four extruders, the company has a production capacity of 100,000 tonnes of super premium pet food and can make batches from 3-200 tonnes to suit small or large brands, delivering the same quality and consistency whatever the batch size.

A reliable electrical equipment provider should have a clear understanding of the application as a whole, the machine itself and the components. This way, CP Automation is able help make the manufacturing process more efficient, more cost effective and more sustainable in every sense.

Benefits of universal peripherals

There is a real danger in the specification of inverters for use in heavy-duty applications. Fresh from the manufacturer, most drives — even ones with onboard brake choppers — are not rated sufficiently for the braking demand of the application. Here, John Mitchell of CP Automation, discusses the benefits of using a universal brake chopper that works with any inverter.

Non-specialist engineers face an extremely complex task when asked to choose the correct inverter, resistor and brake-chopper combination for a project.

To help counteract this problem, CP Automation recommends using an external brake chopper unit that simplifies the process of inverter selection. Where an inverter doesn’t feature a built-in brake chopper, the new CP Automation unit, manufactured to the highest standards, supplies that functionality. It’s a universal model that works with any inverter, from any manufacturer.

However, the fact that a product is universal doesn’t simplify the selection process by itself. You also need to ensure that you choose the right integration and maintenance partner, so you are not tied into a limited range of drives from a limited range of manufacturers.

A good maintenance partner will provide an honest view of whether you already have the correct resistor and, if you don’t, supply one as part of a package to help meet your specific objectives.

For instance, if the original inverter already has a brake chopper onboard it may be that the Ohmic value of the existing resistor doesn’t meet the criteria of the new one. This can lead to damage to the drive system and its environment and in worst-case scenarios, create health and safety problems.

CP Automation's universal unit is very flexible and extremely simple. The maintenance engineer simply connects two wires from the drive’s DC Bus and two wires from the resistor, and the system is up and running.

An additional benefit of the product’s universal nature is that, should you install a brake chopper and inverter package and the inverter then fails, the end user can simply install any drive, from any manufacturer. The brake chopper and resistor package doesn’t tie the user to certain equipment, as the equivalent bought direct from the drives manufacturer would.

This means manufacturers can bring a production line back to full service quicker than if the brake chopper and resistor package worked with only one inverter model.

It is also possible to re-deploy inverters in use on less critical equipment to mission critical applications without fear of incompatibly. CP Automation's brake chopper even finds applications in motion control drive solutions, where it is equally applicable due to the common DC bus.

A DC bus drive system configuration provides users with significant advantages including design flexibility, higher efficiency and inverter power sharing as well as cost savings. These are realised through reduced cabling and fewer components — such as resistors and thermal devices.

CP Automation routinely keeps extensive stocks of brake choppers in its warehouses, with the smallest unit being 11kW continuous, 33kW peak, and the largest being 100 kW continuous, 360kW peak and users can parallel up above this to create BC units greater than 1MW.

In the drives industry there is a genuine belief that all AC inverters are created equal. This situation is exacerbated by the fact that inverters are often bought as commodity items, much like control gear. But the reality is that, at least with regard to dynamic braking, this couldn’t be further from the truth.

Increased efficiency for uninterruptable power supply

CP Automation now distributes and fits the REVCON boost converter module RSU as part of its range. This unit enables highly efficient uninterruptable power supply (UPS) of variable frequency drives (VFD). This compact power unit has huge cost saving implications for anyone that uses power loss ride through in their processes.

UPS systems provide an electrical supply that is converted from batteries when the mains supply is lost in situations such as brown outs, unstable supplies or emergency lift evacuations. The REVCON boost converter module RSU is set to change the way factories maintain their power supply.

"Traditional UPS systems lead the power to the VFD through the complete UPS application, even when power supplies are operating normally," said John Mitchell, global business development manager at CP Automation. "This results in unnecessary power losses due to rectification and invertation of the voltage.

"By adding a REVCON boost converter to the system, the UPS remains inactive when power supplies are working normally. This means the VFD is supplied directly by the mains, rather than having the middle-man UPS system causing unnecessary power losses."

When the mains power supply is down, the REVCON boost converter is activated and sets the voltage value from the batteries to the required level of the VFD. This maintains the power supply in the DC bus to the VFD, without any interruption.

This simple principle enables a highly efficient, yet inexpensive option for uninterruptable power supply to VFD drives. While conventional UPS systems have an efficiency of 90 to 95 per cent, adding a REVCON boost converter means the UPS setup will have efficiency greater than 99.5 per cent. This has huge cost saving implications for a range of industries that use power loss ride through in their processes.

CP Automation is available to supply and install the REVCON boost converter module RSU. For more information about CP Automation's catalogue of REVCON products, go to www.cpaltd.net.

Common causes of electric motor failure

Modern electric motors may be more efficient and reliable than their ancestors, but they can still fail sometimes. Here, Martin McGuffie, service manager of Euroserv, sister company of CP Automation, explains the three common causes of electric motor failure and how maintenance staff can reduce the impact equipment failure can have on business.

How long do electric motors actually last before they break down? The answer is often disputed, with some manufacturers stating 30,000 hours and others suggesting they can power through for up to 40,000 hours. However, most manufacturers are in agreement that electric motors last much longer when maintained properly.

Understanding the state of an electric motor’s health requires a range of tools and techniques, as well as thorough record keeping and regular maintenance. This allows the engineer to identify trends or weak points more easily.

Weakened insulation

Nearly half of electrical failures in motors begin with weakening of the insulation around individual wires in the motor coils. This is often caused by thermal stress, contamination and movement of the winding due to the magnetic forces during start-up and shut-down of the motor.

Overheating can also cause the winding insulation to deteriorate quickly — for every ten centigrade rise in temperature, the insulation life is cut in half. Overheating can occur when the power quality is poor or when an electric motor is forced to operate in a high-temperature environment.

Contamination

Contamination is another one of the leading causes of motor failure. Contaminants include airborne dust, dirt or any abrasive substance that finds its way into the motor. When they come into contact with the motor, foreign bodies can cause denting of the bearing raceways and balls resulting in high vibration and wear.

Luckily, preventing contamination is fairly easy. Main sources of contamination include dirty tools, work areas and hands. Motors can also be contaminated by foreign matter in lubricants and cleaning solutions.

Engineers should keep work areas, tools and fixtures clean to help reduce contamination failures. Also, when laying out the space, companies should try to keep motor assemblies and operation areas away from grinding machines to reduce the amount of foreign bodies that might contaminate the motors.

Lack of maintenance

A well-planned preventative maintenance programme is the key to dependable, long-life operation of motors and generators. It also helps reduce unscheduled production stoppages or long repair shutdowns.

The first step towards preventative maintenance is understanding how often tests need to be carried out on the motor. This varies, depending on the age, condition and quality of the machine, as well as the environment it operates in.

Static tests are an easy method of identifying weaknesses within the motor winding. The tests focus on winding and insulation resistance, as well as turn-to-turn and phase-to-phase insulation condition. With the right equipment, these tests can be performed without taking the motor off site, thus minimising downtime.

Motor testing and analysis equipment, such as Euroserv’s SKF Static Motor Analyzer Baker DX, can survey all insulation and windings in AC and DC motors, coils and generators. During a site visit, Euroserv attends with the all-in-one tester, providing customers’ maintenance staff an analysis of the condition of the impedance, capacitance, phase angle, resistance, insulation and step voltage.

Motor failure can cause downtime, meaning companies can lose thousands of pounds every minute when operations are stopped. Instead of exposing themselves to downtime, customers should request regular motor testing and analysis, ideally every six months, to ensure their electric motors are healthy, efficient and reliable.

To find out more information about the SKF Static Motor Analyzer Baker DX, get in touch with Euroserv here.

Don’t let harmonics get you down

In 1976, it was discovered that the bacteria causing Legionnaires disease, an atypical strain of pneumonia, had always been present in water, but it was the precise temperature of the water in heating, ventilation and air conditioning systems that facilitated the bacteria’s maximum reproduction levels. This is just one example of the unintended consequences of technology.

A similar and more recent story comes from the world of industry and features the growing problem of harmonic currents and utility level voltage distortion, as a result an increasing number of non-linear loads in industrial and commercial environments. Here, John Mitchell, global business development manager of CP Automation, shares his top tips for companies that want to commission or replace harmonic filters.

Active versus passive

The first thing you should decide is whether you need a passive or an active harmonic filter. The traditional option is an electro-mechanical or semiconductor controlled passive filter, used to minimise power quality problems in the network. These filters operate mainly on a fixed basis and are tuned to a harmonic order close to the order to be eliminated.

Often new equipment is specified to meet a THID%, but the problem for many plants is they do not know how bad their site is already. It’s almost like fixing a sticky plaster to a deep wound. Instead, companies should look at what is physically and commercially viable in the long term.

When making a decision, you can also consider a mixed solution. By fitting passive filters on many applications, you should be able to add a smaller active solution, which can save a lot of costs depending on the plant.

One drawback of passive filters is that they are most efficient when the load is operating above 80%.

On the other hand, active harmonic filters continuously monitor the network and inject exactly the right amount of compensation current when it is needed. The filter compensates the harmonic current or voltage drawn by each load. This allows current waveform to be restored instantaneously and lowers current consumption.

For installations in which current load changes constantly, active harmonic filters work best. They can filter harmonics over a wide range of frequencies and adapt to any type of load.

Regardless of what type of harmonic filter you decide to use, make sure it has the relevant UL certifications for the environment in which it's going to run. If unsure, you should always refer to an expert.

Holistic approach

Before commissioning a harmonic filter for your application, it’s important to assess the entire system, calculate the harmonics and size the right solution for your specific set up. It is not enough to look at one troublesome application individually; instead, you need to look at the plant or entire operation as a whole. Often what looks like the problem can actually be an effect rather than a cause.

Companies should identify and understand all the components installed on site when it comes to both linear and non-linear loads. They should also be aware of the transformer size and the rated short-circuit breaking current. Only after understanding the system in its entirety, can a company make an informed decision on what type of harmonic filter it needs, as well as what capacity and additional features the filter should have.

CP Automation recommends performing a survey of the plant and capturing as much information as possible over several days. After this initial analysis, we can recommend the most appropriate product and install it without significant disruptions.

After the harmonic filter has been live for a several days, another survey should be performed to check if all problems have been resolved. This ensures the product is appropriate and it gives companies real peace of mind.

The increasing levels of harmonic currents in industrial and commercial applications are certainly an unintended consequence of rapid technology uptake. Luckily, like the Legionnaires disease bacteria problem, the solution is simple, sustainable and inexpensive. Moreover, if you’re unsure of what harmonic filter your system needs, help is never too far away.