SURGE PROTECTIVE DEVICES

Transcription

1 SURGE PROTECTIVE DEVICES 1. INTRODUCTION In order to ensure safety of people, protection of equipment and, to a certain extent, continuity of supply, insulation co-ordination aims at reducing the likelihood of equipment dielectric failure. Several components can be used to limit and/or eliminate the surges. This document provides general specification for the surge protective devices (SPDs) to be installed in LV electrical systems. SPDs shall be installed near the origin of the installation or in the main switchboard assembly, however additional SPDs might be necessary to protect sensitive equipment and when the distance from the main SPD to the next distribution board is big (> 30m). These secondary SPDs shall be coordinated with the upstream SPDs. 2. SPECIFICATIONS 2.1. STANDARDS The accomplishment of the following standards are required: STANDARD EN Type 1, Type 2 and Type 3. Surge protective devices connected to low voltage power distribution systems. Part 1. This is the European variation of IEC which is mandatory in European countries IEC Class I, Class II and Class III test Edition 2 ( march 2005): Surge protective devices connected to low voltage power distribution systems. Part IEC Electrical installations of buildings - Part 4-443: Protection against overvoltages of atmospheric origin or due to switching IEC Electrical installations of buildings - Part 5-534: Devices for protection against overvoltages IEC Degrees of protection provided by enclosures (IP code) 2.2. CERTIFICATIONS Both EN & IEC Certifications are required CE marking (to IEC Class I, Class II and Class III test) METHOD Third Party Lab Third Party Lab or self certified A safety mark of conformity shall be required: ÖVE, NF, KEMA,. SPD Engineering Specification Latest.doc 1

2 2.3. SURGE CURRENT RATINGS AND PROTECTION LEVELS Iimp (Type 1)/ Imax (Type 2): The value of Iimp shall not be less than 12,5kA for each mode of protection [IEC ]. In case the connection type 2 is used (see ) the value of Iimp (N-PE) shall not be less than 50 ka for three-phase systems and 25 ka for single-phase systems [IEC ]. The preferred values for the impulse current for Type 1 test SPD are 35 /50 ka (L-PE or L-N), 50kA (N-PE single phase systems when using connection type 2) and 100kA (N-PE three phase systems when using connection type 2) The preferred values for the maximum surge current rating Imax for Type 2 tests SPDs are 8kA, 20kA, 40kA and 65kA. In: The nominal discharge current In shall not be less than 5kA for each mode of protection [IEC ]. Up: The protection level of the protective device (Up) shall not be higher than the level of overvoltage category II (2,5kV) [IEC ]. If sensitive electronics is to be protected the protection level shall not be higher than 1,5 kv. Uc: For a 230/400V network it is recommended the Maximum Continuous Operating System (Uc) to be no less than 340 V. Response time: The response time of Type I SPD shall be no more than 1μs, the response time of Type 2 SPD shall be no more than 25 ns MECHANICAL REQUIREMENTS SPD Engineering Specification Latest.doc 2

3 2.4.1 Housing Material Housing material must conform the necessary standards (including self flame-extinguishing characteristics), Required Housing Markings Compliance to IEC Section Test certification marks Terminal Connection 35mm2 is preferred End of Life Indicators All products (except products to be connected N-PE) will have an End of Life visual indicator. The indication shall be LED or mechanical. If LED is used must be ON for normal operation (green color). When reach the end of life LED or mechanical indication must be Red Mounting Method Standard Snap on 35 mm DIN Rail mounting Shock, Impact, Reference IEC Vibration Enclosure Protection Comply with IEC IP20 rating 2.5. ENVIRONMENTAL REQUIREMENTS Minimum Operating Range -5 C to +40 C Relative Humidity 5% to 90% Altitude 2000 Meters minimum without derating 2.6. ELECTRICAL REQUIREMENTS Remote Indication Thermal Protection Short circuit Protection System Frequency Breaker Coordination Optional. When required use Dry Contacts (250 VAC 1.5A, 125V 3A desired, min Amps at 250V required). Thermal fusing is required for MOVs. Not required for GDTs External dedicated circuit breaker to the SPD is required to guaranty the continuity of service and electrical installation safety in case of short circuit inside the SPDs. 47 Hz to 62 Hz Provide coordinated disconnect device requirements which will be put in the literature and on product as required by the manufacturer recommendations. SPD Engineering Specification Latest.doc 3

4 3 INSTALLATION RECOMMENDATIONS 3.1 SPD configuration depending on the grounding system: TT systems (connection type 2): TN-S, TN-C systems: For TN-S, TN-C systems it can be used connection type 2 (see ) or alternatively connection type 1 as per below (if there is significant distance between the N-PE bonding point it shall be used and additional SPD N-PE): SPD Engineering Specification Latest.doc 4

5 3.1.3 IT systems: 3.2 Connecting conductors: The length of the connecting conductors from the lines to the SPD added to the cable conductor from the SPD to the main earth terminal shall be less than 0,5 m (IEC ). The cross section of the cables shall not be less than 4 mm². When there is a lightning protection system, for type 1 products the cross section shall not be less than 16 mm ². SPD Engineering Specification Latest.doc 5

6 3..3 External dedicated protection: An external dedicated protection will be installed to protect against overcurrent and consequences of SPD failure and to optimize the continuity of service.... SPD Engineering Specification Latest.doc 6