New types of arresters of class I produced by LEUTRON meet the requirements imposed to arresters of class II. Thanks to that, the data systems of arresters with voltage protection level lower than 2500V can be replaced by the existing solutions, consisting of several groups of elements.

The notion of surge arresters of class I/II is introduced with the aim to simplify design and installation.

Examples of such solutions, offered by LEUTRON, are surge arresters of type PowerPro BC 25kA (FM), IsoPro BC 60kA (FM), and also IsoPro BC 25kA (FM).

Dimensions of arresters, their construction and form are similar to arresters of class I. The type of most frequently used arresters of class I/II , intended for TN-C, TN-S and TT networks are shown in fig.2.8.

IsoPro BC TNC 25/75kA IsoPro BC TNS 25/100kA IsoPro BC TT 25/100kA
IsoPro BC TNC 25/75kA IsoPro BC TNS 25/100kA IsoPro BC TT 25/100kA

Fig. 2.8. Types of arresters of class I/II IsoPro

Main parameters of these arresters are given in Table 2.3.

Table 2.3 Surge arresters of class I/II
ARRESTER TYPE PowerPro BC 25 kA (FM) IsoPro BC 25 kA (FM) IsoPro BC 60 kA (FM)
Static response voltage Uagn ≥ 800V 900 ± 20% 900 ± 20%
Nominal operating voltage: 50/60 Hz UN 230/400V 230/400V 230/400V
The greatest long-term operating voltage 50/60 Hz Uc 255 V 255 255
100% response voltage at a lightning strike 1.2/50 ms Uas ≤ 2500V ≤ 2500V ≤ 2500V
Voltage protection level    Up ≤ 2500V ≤ 2500V ≤ 2500V
Rated pulse current 10/350 ms limp 25 kA 25 kA 60 kA
Maximum preceding safety device   250 A gL 160 A gL 160 A gL
Insulation resistance Risol ≥ 1010 Оhm ≥ 1010 Оhm ≥ 1010 Оhm
Response time tA ≤ 50 ns ≤ 50 ns ≤ 50 ns
Operating temperature areas υ -400...+850 -400...+850 -400...+850
Level of protection, provided by the case   IP 20 IP 20 IP 20
Item number     LE-373-825 LE-373-830
Item number (version with performance tracking)     LE-373-826 LE-550-518
Assembly   On a bus of 35 mm

Surge arresters of class I/II are characterized by the voltage protection level lower than 2500 V and provide main protection of electrical equipment on building sites, equipped with lightning protection system.


2.3. Universal surge arresters of class I / II / III

The next stage of development of class I arresters is application of multi-chamber spark gaps, providing voltage protection level lower than 1000V, these are the so-called surge arresters of class I/II/III (fig.2.9), carrying out requirements of test area of classes I, II and III.

Arrester PowerPro BCD-1 Arrester PowerPro BCD-2
a) arrester with a pair of clamps for connection to phase and neutral conductor b) modular system of arresters for TN-C system

Fig.2.9. Arrester PowerPro BCD

New generation of spark gaps, placed in gas, is used in these arresters (fig.3.10), which provides voltage protection level lower than 1000V.

Mult-chambers park gaps of a universal device for overshoot suppression

Fig.2.10. Mult-chambers park gaps of a universal device for overshoot suppression

Проводник- conductor
Электрод- electrode
Керамический корпус- ceramic case
Камера разрядная – discharge chamber
Разрядник многоразрядный- multi-discharge spark gap
Охлаждение стойкое к высоким температурам- cooling resistant to high temperatures
Пайка импульсная-pulse soldering
Электрод- electrode

Universal surge arresters PowerPro BCD if compared to typical arresters of class I, have the following advantages:

  1. They provide protection of electrical equipment and energized devices from the impact of lightning current part and all kinds of surge voltages.
  2. They can be used for protection from direct lightning strike in accordance with a certain level of lightning protection.
  3. They meet the requirements of test area of classes I, II and III.
  4. Voltage protection level of these arresters is lower than 1000 V.
  5. They are characterized by simple design, with spark gaps only without any additional control elements or elements enhancing operation, which reduces their breakdown.
  6. It has an indicator of spark gap's damage (reaction to overheating of the spark gap).
  7. Simple protection system consisting of only 3 or 4 arresters.
  8. Can be used in all types of construction objects.
  9. Arresters can be assembled in a parallel or sequential system Arresters PowerPro BCD don't require additional safety devices, if values of phase fuses do not exceed 250 A gL/gG and 100A gL/gG (for parallel and sequential systems correspondingly).
  10. Construction of protection systems made of one-phase arresters brings to the fact, that there appears a chance of light and cheap substitution of separate arresters in case of their damage. No change of a whole protection panel, like in other solutions, is required.
  11. No protective distances between the arresters and neighboring technical devices (in the used spark gaps, there is no gas emission from the arrester).

I/II/III class arresters found wide use in electric equipment of small objects, in which there are electronic devices, for example containers or secure cabinets with telecommunication devices or control and measurement instrumentation, base GSM stations.

In case of base stations, the need to apply arresters with such a low voltage protection level comes out of relatively low level of shock withstand of working devices.

Main parameters of these arresters PowerPro are given in table 2.4.



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