Technology Live Workshop David Pitt Product Manager Eaton Electric Ltd.
Technology Live Workshop Subjects to be covered in this Technology Live Workshop: Increased need for installation of transient voltage surge protection devices / Amendment-1 of the 17 th Edition Wiring Regulations. Latest developments in earth leakage protection and monitoring. 2
Surge Protection Why the Increased Need? Electronic equipment is being used increasingly in our environment and we are more dependent upon it s efficient and continuous running. Physical size of this equipment has reduced considerably over time which makes it more susceptible to damage by transient overvoltages which can cause: Catastrophic failure. Premature ageing / degradation. Incorrect operation. 3
What is a Transient Overvoltage? Transient overvoltages (also known as spikes ) in electrical transmission and distribution networks result from the effects of lightning strikes or electrical switching operations. They are of very short duration, from microseconds to a few milliseconds, and can be up to several thousand volts. 4
Causes of Transient Overvoltage External and internal influences can cause transient voltage spikes on mains voltage, data, and telecom circuits. Major causes: Externally caused effects of lightning and utility grid switching. Internally caused switching of equipment and operation of some appliances. Internal 65% External 35% 5
Surge Protection Part of Amendment 1 of the 17 th edition IET Wiring Regulations provides for increased criteria to provide adequate protection for both people and equipment from transient overvoltages of atmospheric origin via the supply distribution system and against switching events. Section 443 covers the requirements for when surge suppression is required to be installed. Section 534 details the specification of surge protection devices and the types required. 7
Principle of Surge Protection Surge protection devices (SPDs) are designed to limit transient overvoltages and divert the associated energy to earth. This limits the level of the overvoltage to a value that would not cause damage to the electrical installation or equipment. Surge protection works like a series of increasingly finer silencers (T1 to T3). Downstream of each of which the destructive force becomes less until minimised to a level that can be withstood by the equipment. T1 T2 T3 8
Principle of Surge Protection When lightning strikes overhead power lines the utility company provides some protection whereby part of the energy is discharged into the earth through the pylons. However significant current spikes flow into the building through the power supply line. Very little attenuation is provided by transformers. There are three main types of SPD defined in IEC 61643-1 for low voltage power distribution systems. 9
Principle of Surge Protection Type 1 SPD ( coarse level protection) T1 The Type 1 SPD is recommended in certain circumstances to protect electrical installations against direct and indirect lightning strikes. It is typically located in the first distribution system after the service entrance. Type 1 SPD is characterised by its ability to limit a 10/350 μs current wave typical of a lightning strike. (Similar specification to previous Class B devices). 10
Principle of Surge Protection Type 2 SPD ( medium level protection) T2 The Type 2 SPD is often the main protection system for low voltage electrical installations. Installed in electrical distribution equipment, it prevents the spread of overvoltages in the electrical installations and provides general protection for most loads. Type 2 SPD is characterised by its ability to limit a 8/20 μs current wave, typical of a switching surge. It is often normal practice to combine Type 1 and Type 2 SPDs in a composite unit. (Similar specification to previous Class C devices). 11
Principle of Surge Protection Type 3 SPD ( fine level protection) T3 These SPDs have a low discharge capacity. They must therefore only be installed as a supplement to Type 2 SPD and in the vicinity of sensitive loads. Type 3 SPD is characterised by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs). (Similar specification to previous Class D devices). 12
Principle of Surge Protection All SPDs have a local status indication, usually through a green flag to indicate protection is being maintained. In the event of the SPD reaching an end of life status the flag will turn to red. The SPD status can be remotely monitored by the addition of an auxiliary switch which can be hard wired or network linked back to a monitoring system. 13
Other Types of Electrical Disturbance Transient voltage surge protection devices do not protect against: Sustained overvoltage being provided by the supply system. Radio frequency interference causing distortion of the normal sine wave. Harmonic frequency distortion of the normal sine wave. Electrostatic discharge. 14
BEAMA Surge Protection Guide Recommended reading! Earlier this month BEAMA published its Guide to Surge Protection Devices which provides clear, best practice guidance to understand the types of risk and damage that can occur, and enable compliance with surge protection requirements in Wiring Requirements BS 7671. http://www.beama.org.uk/en/news/ 15
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Technology Live Workshop Subjects to be covered in this technology live workshop: Increased need for installation of transient voltage surge protection devices / Amendment-1 of the 17 th Edition Wiring Regulations. Latest developments in earth leakage protection and monitoring. 17
Latest Developments in Earth Leakage Protection and Monitoring. Enhancements in functionality of residual current devices through the use of new Digital Electronic Technology (DET). Alarm 50% I Δ N Warning >30 50% I Δ N OK 30% I Δ N 18
Why Use Digital Electronic Technology? The IEC Standards for RCCBs and RCBOs allow for an earth fault tripping tolerance of between 50% and 100% of the device s nominal ma sensitivity. Eaton s digital electronic technology enables these devices to be much more precise in holding the actual trip current close to the 100% sensitivity level. Accurate level of leakage is identified through coloured LEDs. Test & service mode available on RCBO. RCBO RCCB 19
RCBO LED Status / Service Mode LED Status Mode LED Service Mode Alarm 50% I Δ N Warning >30 50% I Δ N OK 30% I Δ N 20
Benefits of Digital Electronic Technology DET features are a unique offering in the market. Pre-warning to solve problems without interruptions. RCCB has local and remote indication of system status via bus system, GSM, or xcomfort wireless system. Extended push to test interval 1 year. Increased level of accuracy. Potential for reduction of unscheduled downtime. Display of leakage current. Indicator flag for earth fault current trip. 21
New - Earth Leakage Current Monitor LEDs >50% I Δ N >30-50% I Δ N <30% I Δ N Displays the actual leakage current status through coloured LEDs. 2 auxiliary contacts to remotely indicate leakage level greater than 30% I Δ n. Intended for preventive information / monitoring (e.g. for processes where continuous system availability is required) 30-50% I Δ N >50 % I Δ N 22
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