Electrical installations in industrial buildings and plant need protection through the use of SPDs against the risk of damage or destruction by voltage surges caused by lightning and inductive circuits. Only dedicated SPDs can provide full protection for electronic and electrical devices which means protection should be tailored to the application. The range of applications invariably involves a combination, if not all, of power distribution, control and instrumentation signals, and discrete device protection.
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Surge protection for power distribution
Surge protection sytems for industrial applications should be designed to relate to the – protection classes I to III without the use of decoupling modules. (In the past was it only possible to use class I and II in series with special lengths of cable or additional inductors.)
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For this reason, the PU I-III family of surge protectors based on varistor technology – is a totally reliable solution for the protection of electrical devices.
Lightning and overvoltage protector type PU I offers the performance to cover the first level of protection (class I or II) in power distribution circuits. The PU I, with its high discharge current of 12.5 kA (10/350μs), fits into any subdistributor and switching system thanks to its first-class design with low space requirements.
Its core element, the high-performance varistor, is designed as a pluggable component and is thermally triggered on overload in the event of a fault. Following the fault signalling, which is indicated by the red/green function indicator, the pluggable arrester module can be easily replaced. Through the use of standard cross connection, it is possible to shorten cable lengths (e.g. to the RCD).
The 180° turnable and pluggable high-performance varistor guarantees a strong and definite visual status in the control cabinet. The PU I can be used problem-free without decoupling in the protective system with class II and III arresters. With the overvoltage arresters of type PU I up to the PU III terminal device protection, a three-level protection concept can be created without difficulty.
Surge protection for control and instrumentation signals
Much more sensitive are the interfaces in the Control and Instrumentation (C&I) sector. Possible coupling of overvoltages along lines can interfere with or destroy sensitive signal inputs. It is important to protect C&I devices in their immediate vicinity in order to protect them from electro magnetic pick-up on their interconnecting cables. With a comprehensive product line for the C&I sector, Weidmüller offers products in terminal block format with tension clamp MCZ series) and screw connectors (DKU series).
These products are designed for digital current loops as well as analogue signals. Furthermore, Weidmüller also offers terminals with integrated components such as gas discharge tubes or varistors, to maximize the physical options for users.
Surge protection in the data sector
In the data sector it is of course important that data is sent from the transmitter to the receiver without transmission losses and corruption. This is best achieved by having a series protection component integrated into the circuit.
Thus, as a passive element, the surge protection device must not influence the flow of data and must trigger in the event of a protection incident. This is a feature of the MCZ OVP HF. With low attenuation values, particularly with respect to high transmission rates, the MCZ OVP HF is the best choice. The tension clamp technology employed successfully at Weidmüller for decades, and now, combined with the newly designed and unique directly mountable Omega-spring-PE-rail contact, installation time is reduced even further. With a width of just 6 mm, the terminals contain high-quality overvoltage protection electronics whilst minimizing rail space. This protective circuit is well suited for applications such as fast data transmission or very fast analogue systems. The discharge characteristic of the Omega- spring/PE-rail-contact is designed for 10 kA (8/20μs).
Through this variety, it is possible to achieve effective protection and therefore highest availability of electrical and electronic systems.
All of the mentioned Weidmüller products can be used world-wide, as they have successfully passed a wide range of standardisation tests and been granted numerous approvals. These includes for example, being tested according to EN 61643-11 and IEC 61643-21 and approval granted according to UL497B.
Weidmüller offers many other products in the overvoltage protection sector, such as coax overvoltage protection and
spark gaps for the highest requirements in lightning protection.
