Overvoltage Protection in IP CCTV LAN-RING Systems

Transcription

1 Overvoltage Protection in IP CCTV LAN-RING Systems rev Introduction This application note contains the rules for correct connection of overvoltage protections in IP CCTV systems LAN-RING. According to the place of installation we distinguish two basic situations: Indoor installation Installations are protected by overvoltage protections of class I.,II.and III. according to IEC Typical representatives are camera placed for conversion in the production halls of heavy industry, office and commercial premises. Installations are not protected by overvoltage protections of class I.,II.and III. according to IEC Typical representatives are camera placed on the post along a fence, on outdoor walls, roofs etc. When considering the need of overvoltage protection it's importnat to take the length of connecting cables into account. See the table on the following page. Overvoltage protections resolve only device protection from excessive voltage coming over the cables. It's necessary to consider also lightning protection; according to e.g. standard IEC property can be divided into 4 levels according to risk of material damage or loss of human lives. Class LPL III and IV family houses, agricultural property... Class LPL II industrial and administrative buldings... Class LPL I power plants, hospitals, buldings with danger of explosion... In all cases it's important to instal overvoltage protections as close to the protected device as possible and ensure proper grounding (see below). By general rule the overvoltage protection is only as effective as its weakest link. Therefore, it's necessary to apply 1/5

2 overvoltage protection to every port with possible danger of overvoltage. Note: Overvoltage protections do not protect the device from prolonged overvoltage lasting seconds and minutes and are dimensioned only for impulse currents (e.g. 10/350µs, 8/20µs, 10/1000µs etc). 2 Overvoltage protections integrated in LAN-RING switches IP CCTV LAN-RING switches and media converters contain 5 types of ports 2.1 supply input 48VDC (48VDC) 2.2 fast ethernet ports acc. to IEEE802.3 with support of PoE+ acc. to IEEE802.3-at 2009 (FE port) 2.3 gigabit ethernet ports acc. to IEEE802.3 (GE port) 2.4 relay outputs (RELAY) 2.5 digital inputs (DI) Is it necessary to instal additonal overvoltage protections to a port? PORT Indoor installation (cable max. 10m) (cable over 10m) SUPPLY 48VDC no no yes* FE port no no no GE port no no yes* RELAY no no no DI no no yes* * Class III acc. to EN Power supplies and transformers LAN-RING system includes industrial power supplies and toroid transformers. Supplies SU- 230/4870H and toroid transformers TRF-2410T-IP55H are equipped with overvoltage protection class III acc. to IEC The following table provides overview of the need to instal additional overvoltage protections to 230VAC feeding. Is it necessary to instal additional overvoltage protections to 230VAC cable? Type Max. output power Operation temperature Indoor systems Outdoor systems SU-230/4870H 70W -40 C C no no* ML W 0 C C no yes TRF-24100T 100W -40 C C no yes TRF-24100T-IP55 100W -40 C C no yes TRF-24100T- IP55H 100W -40 C C no no* QS W -25 C C no yes 2/5

3 * Standard EN defines 4 lightning protection levels (LPL). For objects with the highest risk (LPL1) we recommend considering installation of additional protections of class II and I acc. to IEC We also recommend to lead the 230VAC feeding through premises protected by air termination network leading to reduction of the risk of direct lightning strikes and possible damage. 4 Requirements for grounding of overvoltage protections of switches in BOX The basis of the proper functioning of overvoltage protections is their grounding and correct installation of supply cables. 4.1 Ground resistance must not exceed 10 Ω. With higher ground resistance efficiency of overvoltage protections decreases. 4.2 Grounding of switches must be realized using a cable of min. 4mm 2 diameter. 4.3 Grounding cable length should be kept as short as possible, i.e. for pole installations it's necessary to use grounding electrode of the pole. 4.4 For grounding any of the following can be used: a PE terminal board of the closest switchboard, a grounding electrode (poles), grounded constructions. 4.5 Down lead of a lightning conductor cannot be used for grounding. 5 Requirements for grounding of overvoltage protections of switches in RACK 5.1 Ground resistance must not exceed 10 Ω. With higher ground resistance efficiency of 5.2 For grounding of the switch use PE cable of the 19 rack 230VAC supply feed. 6 Requirements for grounding of overvoltage protections of switches in IP Ground resistance must not exceed 10 Ω. With higher ground resistance efficiency of 6.2 Grounding of switches must be realized using a cable of min. 4mm 2 diameter. 6.3 Grounding cable length should be kept as short as possible, i.e. for pole installations it's necessary to use grounding electrode of the pole. 6.4 For grounding any of the following can be used: a PE terminal board of the closest switchboard, a grounding electrode (poles), grounded constructions. 6.5 Down lead of a lightning conductor cannot be used for grounding. 3/5

4 7 Requirements for grounding of overvoltage protections of IP cameras 7.1 The protection must be installed close to the camera. 7.2 Ground resistance must not exceed 10 Ω. With higher ground resistance efficiency of 7.3 Grounding of COP series protetcions must be realized using a cable of min. 4mm2 diameter. 7.4 Grounding cable length should be kept as short as possible, i.e. for pole installations it's necessary to use grounding electrode of the pole. 7.5 For grounding any of the following can be used: a PE terminal board of the closest switchboard, a grounding electrode (poles), grounded constructions. 7.6 Down lead of a lightning conductor cannot be used for grounding. 8 Recommended types of overvoltage protections for IP cameras Device / port Indoor installation (switch METEL to 10m) IP camera / FE port with PoE IP camera / FE port + supply feed 24VAC (switch METEL > 10m) - - BREAK-100M/PoE-B-BOX - BREAK-100M/24-BOX or separate protection to 24VAC feeding BREAK-100M/24-BOX 9 Example Connection of overvoltage protections of 2G E-IP65 switch in outdoor environment 4/5

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