Sparks Electrical News January 2023

EARTHING, LIGHTNING &SURGE PROTECTION

10

Beyond the surge protection device

The Pepperl+Fuchs M-LB 5000 surge protection system S urge voltages have many possible causes. operations and load drops and interruptions to the supply. There are other effects in addition to the direct destruction of components, in particular the risk posed to plant availability and the resulting consequences, such as production downtime, which drives operating costs up. Surge protection systems must therefore form an integral part of process engineering plants. In addition, current standards such as EN 62305 (SANS 62305) require that the effectiveness of these systems be checked regularly. Up to now, this check has usually been carried out manually on-site, which is costly for large plants in particular and requires trained personnel and tools such as a test kit. However, the test results do not give any indications of prior damage to the protection module and its state of wear. It has previously only been possible to rate the tested devices as ‘good’ or ‘bad’. To meet the different safety requirements of the signal line market, Pepperl+Fuchs offers two surge protection systems with different functions. Surge protection with conditionmonitoring The M-LB-5000 surge protection systemwith condition monitoring function monitors signal lines automatically and continuously. The patented diagnostics use a special algorithm to detect the different load situations that cause the surge protection system to wear. This includes counting the number of times the gas discharge tube has ignited, detecting the silicon temperature of the suppressor diodes and measuring the interior temperature of the surge voltage protection module. When the protection module has reached 90% of its useful life, this is indicated by a yellow diode. The protection modules are therefore replaced neither too early nor too late: replacing them too early leads to an unnecessarily high replacement frequency, while replacing them too late leads to the plant having phases without sufficient surge protection if defective modules are not replaced immediately. This optimises the availability of the surge protection functionality and of the plant and at the same time minimises maintenance costs. The M-LB-5000 modules are mounted on a standard DIN mounting rail. The devices each consist of a base module and the actual protection module. The system also has an insulating partition to maintain clearance when mounting Ex and non-Ex modules on a DIN mounting rail. All modules have a width of only 6.2 mm and allow simple commissioning without special aids. In addition to the protection and base modules, there Electronics can receive sustained damage from lightning strikes, transients caused by switching • Detailed amplitude values of the sine wave. • Frequency (which should be 50Hz in South Africa). • Flicker (a measurement that indicates flicker in light sources). • Voltage drops or overvoltage. • Interruptions in supply. • Asymmetry (where sine waves are shifted). • Harmonics • Sudden voltage changes. The importance of power quality

are three function modules. The maintenance module reports when a yellow LED lights up on at least one protection module, indicating that this module should be replaced. The fault module indicates when at least one device has a fault (red LED) and needs to be replaced directly. The third unit is a power module that powers the protection modules via the power rail. The error messages are also sent to the function modules or the control panel via the power rail. Terminal block with surge protection Pepperl+Fuchs has developed the M-LB-2000 for applications requiring only minimum specifications, plus loop connect. It has a form factor very similar to the M-LB-5000 and is designed to be attached directly to the DIN mounting rail. The main differences are that the module cannot be diagnosed or replaced without interrupting the signal line. A loop disconnect function is achieved when the module is plugged in via two easily accessible switches on the front. The M-LB-2000, which is also only 6.2 mm wide, not only saves a lot of space in the switch cabinet, it practically replaces the terminal block with surge protection. This means that disconnect terminal blocks are no longer necessary, saving costs. The certificates range from ATEX, IECEx, Zone 1 and SIL 3. Conclusion The M-LB-5000 surge protection system’s diagnostics use a special algorithm to detect different load situations and send a signal when the protection module has reached 90% of its life cycle. This significantly increases the efficiency of the protective function and keeps maintenance costs to a minimum. The modularity of the device enables the protection module to be replaced without tools and without interrupting operation. The M-LB-2000 with loop disconnect function is designed for significantly lower requirements in surge protection. With a width of 6.2 mm, it saves just as much space in the switch cabinet and can be used as a replacement for the terminal block with surge protection.

A round 25% of the world’s electrical energy is consumed by electric motors in industrial applications. However, as John Mitchell, global business development manager at supply, installation and repair specialist, CP Automation explains, installing variable frequency drives (VFDs) and surge protection devices (SPDs) are not the final steps in creating ultimate cost-efficiency. A VFD controls the frequency and voltage supplied to an electric motor. By implementing VFDs, many businesses experience an increased bottom line due to increased efficiency and reduced energy costs. However, the VFD is not without its problems – its normal operation can cause negative effects. Issues arise with VFDs due to power fluctuation. This could be caused by an anomalous event such as a lightning strike to the grid, or by lower-level transient surges caused by VFDs countless times a day. These transient surges are a change in fundamental frequency in a microsecond time frame. If not accounted for, they can lead to confusion in electrical systems, such as false zero crossings, false triggering of diodes and timing issues. A basic SPD may be used alongside a VFD to mitigate the damaging impact of high-power surges, yet many users are still faced with unexplainable lockups, downtime and even some failures in surge protection caused by low level switching transient events. This is because typical SPDs are voltage triggered only. Their clamping will only occur at a set point above or below the amplitude of the sine wave and will therefore not act upon low level switching transient events. While the sine wave has remained the same since the late 1800s, the sensitivity of the equipment that is connected to the grid is now much more sensitive. It’s time to bring surge protection up to speed. It’s clear that standard SPDs are not doing enough to protect valuable systems, whether this is in an elevator, factory conveyor or petroleum production equipment. The next step is to eliminate these low level switching transient events. Using surge and transient protection systems such as the SineTamer, offers a new opportunity to protect valuable assets from the transient events that can occur millions of times per day. The frequency attenuation network of SineTamer does this by monitoring the frequency, not just the voltage. Some businesses have already made this investment. In fact, one plant manager at a packaging company was experiencing multiple electrical failures across seven plant areas related to programmable logic controllers (PLC) and power supplies. After implementing SineTamer, the failures decreased from an average of 55% to zero. For too many years, investments made in process technology have failed to reach their promised results, through no fault of their own. It’s simply been due to the electrical environments in which they were placed.

Enquiries: info@za.pepperl-fuchs.com

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In recent developments, some manufacturers have gone beyond these requirements and created devices that can measure switching surges, lightning induced surges (8/20µs) and lightning impulse currents injected into the electrical system (10/350µs). This is typically done by measuring impulses on the earth cable of the electrical system and is useful for detailed root cause analysis, assisting with insurance claims when damage to the system was caused by elements outside the owner’s control. Detailed overview of power quality within an electrical system is measured by means of PQ measurement devices and can prove to be beneficial for the longevity of equipment, ensuring up-time within a facility during production and assisting in keeping the power grid stable. Moreover, being able to monitor and react to power quality deviations remotely with the use of an internet connected smart PQ measurement device is convenient and reduces delays. Considering the challenges in increasingly modern grids, it becomes clear how important smart power quality monitoring is during electrical design and specification for new installations.

Enquiries: www.cpaltd.net

Enquiries: www.dehn-africa.com

SPARKS ELECTRICAL NEWS

JANUARY 2023