Surge protection considerations during elevator modernisation

Advances in elevator technology have been critical facilitators of the high-rise structures that define our urban skylines. However, upgrades in elevator safety, robustness, quality, space efficiency, and performance are needed to support infrastructure development and meet societal needs. Here John Mitchell,  global sales and marketing director at elevator  power solution specialist, CP Automation explains the importance of opting for the right surge protection device (SPD) to reduce unnecessary downtime.

Elevator modernisation can feel like an expensive and time-consuming undertaking. Before embarking on a modernisation project, a thorough survey is undertaken to assess the current performance of the system. Once armed with this information, an assessment of whether a modernisation is necessary and, crucially, whether it makes business sense can begin.

One of the most important considerations should of course be the safety of the passengers, maintenance personnel and the lift system. A more modern, safer elevator that complies with the latest standards and offers improved reliability is clearly the desired outcome. However, an important safety consideration, that is often overlooked, is the effectiveness of the system’s SPD.

Reducing downtime and maintenance costs

Elevators typically have service lives of over 20 years, but during this time their performance can decline, leading to increased maintenance costs, increased energy usage and the risk of downtime.

Modernisation can make elevators more energy-efficient and reduce energy costs by feeding otherwise wasted energy back into the building whenever the elevator is travelling in an out of balance direction, rather than releasing it in the form of heat through braking resistors.

For example, CP Automation’s Magnetek range of elevator products include drives with in-built regenerative technology and also separate regenerative ‘bolt-on’ modules that can be retro-fitted to any existing AC drive to produce substantial energy savings — savings which can be easily calculated using our online Energy Savings Calculator tool.   

However, as the hardware and software used in elevator applications has advanced, this has brought about an entirely new set of problems and maintenance considerations. While this hardware and software is more reliable than ever before, it is also highly sensitive to fluctuations in power surges.

High voltage surges are normally covered by surge protectors. However, traditional SPDs do not account for low level transient surges that can occur countless times a day, exaggerated by VSD usage. Don’t let the name fool you — these transient surges in the sine wave are very damaging to electrical equipment, as the additional peaks and troughs in the sine wave cause confusion to sensitive devices and machines.

This can cause recurring random failures, lockups and deprogramming, such as those experienced by human machine interfaces (HMIs) used in Destination Despatch systems on each floor. So, to protect the electrical control system, the VSD and lift controller from transients, a more sophisticated transient protection system is needed. Downtime and maintenance can be eliminated if the right surge protection such as SineTamer is in place.

Crucially, SineTamer’s frequency attenuation network monitors the frequency, not just the voltage. The engineered transient disturbance filter is designed to monitor all 360 degrees of the sine wave, making it capable of detecting rapid changes in frequency. This vigilance in turn prevents issues caused by false zero crossings of the sine wave.

When approached carefully, modernisation — whether that’s partial or a complete replacement — can lower repair costs, reduce faults and increase energy savings while improving comfort, efficiency, safety and aesthetics. However, it’s important that facilities’ managers do not overlook the importance of protecting this sensitive equipment from harmful power surges.

For further information about CP Automation’s range of elevator-specific products visit www.cpa-ltd.net.

Understanding utility capacitor bank switching transients

According to the IEEE Guide on the Surge Environment in Low-Voltage (1000 V and Less) AC Power Circuits C62.41.1-2002, utility capacitor bank switching transients is an issue that exists in nearly every electrical system. Here, John Mitchell, global sales & marketing director at supply, installation and repair specialist CP Automation, offers an accessible introduction to this topic, and  details why effective surge protection is the answer.

The application of utility capacitor banks has long been accepted as a necessary step in the efficient design of utility power systems. Generally, capacitor switching is considered a normal operation for a utility system and the transients associated with these operations, are largely not a problem for utility equipment.

However, this is not always the case. High voltage surges are normally covered by surge protectors. In contrast, traditional surge protection devices (SPDs) do not account for low level transient surges. These low level transient surges can be magnified in a customer facility, if the customer has low voltage power-factor correction capacitors, or can result in the nuisance tripping of power electronics-based devices, such as variable speed drives (VSDs), which are very susceptible to changes in power quality.

There are a number of transient-related concerns that are generally evaluated when transmission and distribution shunt capacitor banks are applied to the power system. One example of these many switching events that can cause transients on a utility system, is capacitor energising. Due to their regularity and impact on power system equipment, they often receive special attention.

Another example is distribution system overvoltages, resulting from the energisation of transmission system capacitor banks. These can be sufficient to spark over gapped SPDs — typically silicon-carbide (SiC) design. In comparison, gapless SPDs — typically metal oxide (MOV) design, should be capable of withstanding this event.

These transient switching overvoltages might simply damage low-energy SPDs or cause a nuisance trip of power electronics-based equipment. Nevertheless, case histories have been reported of complete failure of end-user equipment.

Other power quality symptoms related to utility capacitor switching include: customer equipment damage or failure, tripping of process equipment, SPD failure, and computer network problems — all of which are highly disruptive.

Similarly, capacitor switch restrike events can produce high-voltage surges that result in severe energy-duty for adjacent SPDs, or damage to unprotected equipment. It is therefore recommended to select a switching device that will minimise the possibility of a restrike event. In addition, it is advisable to protect adjacent equipment with SPDs of appropriate size.

Further application concerns often include:

• Overvoltages associated with normal capacitor energising

• Open line/cable end transient overvoltages

• Phase-to-phase transients at transformer terminations

• Voltage magnification at lower voltage capacitor banks

• Arrester duties during restrike events

• Current-limiting reactor requirements

• System frequency response and harmonic injection

• Impact on sensitive power electronics loads at customer facilities

• Ferroresonance and dynamic overvoltage conditions

While power quality issues can be caused by an unexpected event such as a lightning strike to the grid, issues relating to the threat of lower level transient surges can be and should be mitigated against.

To eliminate the effects of low-level switching transient events, transient protection systems such as SineTamer offer a new opportunity to protect valuable assets from the transient events that occur millions of times, every day. Its frequency attenuation network monitors the frequency, not just the voltage. The engineered transient disturbance filter is designed to monitor all 360 degrees of the sine wave, making it capable of detecting rapid changes in frequency.

Although this article is certainly not intending to be a comprehensive review of this topic, it provides strong evidence for the need to protect equipment from low level transient surges. Choosing the right SPD is therefore a crucial step and shouldn’t be ignored.

For further information see Sections B.2 to B.2.5 of the IEEE Guide on the Surge Environment in Low-Voltage (1000 V and Less) AC Power Circuits C62.41.1-2002. If you wish to discuss your SPD needs contact sales@cpaltd.net.

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.