Prevent damage to equipment and the environment – with one powerful surge protection system

System safety must meet stringent requirements in process technology – reliability and availability play an important role in the continuous production process. A top priority here is the prevention of damage to equipment and the environment, as well as the prevention of hazardous situations. Being able to monitor whether the device used in surge protection is in proper working order is also useful.

How can surge protection be inspected?

Lightning and surge protection standards recommend a regular inspection of protective devices. This can be done by visual inspection if the surge protective device (SPD) has a status display. In the past, this was only the case for SPDs for signal applications and process technology. The reason is insufficient energy in the signal circuit. In such cases, thermal monitoring of components in the SPD does not function reliably.

Intelligent surge protection keeps the user informed at all times of the status of the system

Intelligent Plugtrab PT-IQ surge protection from Phoenix Contact provides a remedy. It allows the status of the protective devices to be monitored continuously via an electric measurement. Leakage currents as well as surge voltage signals are measured at each voltage-limiting component. The measurement results are forwarded to an internal micro-controller and evaluated, and the result of this evaluation is displayed as a status on the protective device. “Green” signals an error-free status, “yellow” that the device is reaching its performance limit and “red” that the protective device is overloaded. This status is also communicated to a central unit – the front module.

This status information can be forwarded to the front module via floating remote indication contacts. For example, either a PLC queries the contacts directly via a wired connection or the status information is integrated into intelligent signaling systems using interface modules. This means that the status of the surge protective devices, even in large systems, can be conveniently monitored in the control room. The service technician can also be notified by cell phone.

Surge protection in explosion-protected areas

Since there is higher risk in potentially explosive structural systems, often with far-reaching consequences for persons and the environment, a lightning and surge protection concept is essential. In general, observation of lightning and surge protection standard DIN EN 62305 [1], applicable for nearly all structural systems, is sufficient. The second part of the surge protection standard describes risk management for structural systems, which takes into account the effects of lightning strikes. The standard relates to all structural systems – even systems with explosion risk in accordance with DIN EN 60079-0 [2].

The “intrinsic safety Ex-i” type of surge protection is useful as a secondary protection measure in this environment. This type of surge protection limits voltages and currents so that a potentially explosive mixture of ignition energy and temperature is not reached. DIN EN 60079-11 [3] is the specific standard for these intrinsically safe circuits. This standard also references the need for lightning and surge protection.

For systems that require high availability, a failure lasting even a short time period is unacceptable. This results in more stringent requirements for surge protection. For such systems, products from the Plugtrab PT-IQ-Ex series from Phoenix Contact are a good choice since they provide predictive information about their own status.

How is suitable surge protection selected?

In addition to standards for explosion protection, the application standard relevant for SPDs – IEC 61643-22 [4] – is also to be taken into account. The IEC 61643-22 (VDE 0845 Part 3-2) describes the principles for the selection, operation, installation and coordination of the Surge Protective Device. Here, the standard describes a multi- stage surge protection concept and the division of the building into lightning protection zones.

A comprehensive zone concept is especially relevant if there is an external lightning protection system. The first protection level, right at the entrance of the building, should conform with the requirement category “D1”. This protection must be powerful enough that it can manage a lightning current of at least 500 A with the pulse shape 10/350 µs.

The second level of the zone concept must fulfill the requirement category “C2” with a discharge capacity of at least 1000 A for pulse shape 8/20 µs. If the voltage protection level is still not sufficient because of sensitive devices, a third protection level with requirement category “C1” is necessary. These protective devices must demonstrate a discharge capacity of at least 250 A for pulse shape 8/20 µs. Using these three categories – “D1” + “C2” + “C1” – the interference energy is reduced to an acceptable value for the device to be protected. These requirement categories are described in IEC 61643-21 [5]. Depending on the installation conditions and the expected interference energy, a single SPD can be used to protect multiple protection zones of a building. In this case, this SPD must be qualified in all three categories.

Conductors are connected quickly and easily with Push-in technology – and removal is convenient, without any special tools

Permanent and error-free installation

Screw connection technology is still used often in surge protection, but if there are many signal lines to install, considerable time can be saved with quick Push-in connection technology. In order to ensure error-free wiring, all protective devices can be integrated into the monitoring concept without any wiring effort. A connector located on the DIN rail is then able to serve as the required connection to the front module.

Summary

For potentially explosive structural systems, there is higher risk, often with far-reaching consequences for persons and the environment. A comprehensive lightning and surge protection concept is crucial here. The use of surge protection with intelligent status monitoring reduces the need for servicing. This is achieved by a monitoring system that signals wear in the protective devices before failure due to overload.