FAQs
1. I require more information on the Helita Pulsar unit – what is it and how does it work?
The Helita Pulsar is an air terminal consisting of a blunt rod and cylindrical body (dimensions, weight etc listed in colour brochure) The Pulsar is part of a greater system comprising air terminal, down conductors and earths. The pulsar firstly (and only) becomes activated by the rise in electric field that characteristic of a lightning strike. The blunt rod collects this. The atmospheric electric field on the ground, about 100V/m in fine weather, is reversed and reaches an absolute value or 15-20 Kv/m when a ground discharge is imminent (the lightning stroke)
The cylindrical body of the pulsar unit contains specialised capacitors that store energy from the natural build up in electric field (from 100V/m to 15-20Kv/m) and a patented ‘triggered device’ that emits the stored energy as a high voltage signal with a controlled frequency and amplitude.
It is the early formation of this high voltage signal combined with its continuous propagation to the approaching downward leader (lightning strike) that ensure the capture (and consequent earthing) of the lightning strike. As the lightning strike is captured at a high altitude, the strike is less affected by local ground conditions and so ensures a more predictable striking environment (i.e. avoidance of side striking). Once the strike is collected, it is earthed via conventional down conductors.
2. How has the Pulsar been tested?
The pulsar has been tested in laboratories in accordance with the operating principles outlined above (Appendix C, standard NF C 17-102) and performance and efficiency validated by certification organisations such as British Standard (BSI), LCIE and KERI. (See page 6 of attached folder) more recently, the Pulsar has been subjected to strikes from laser in Canadian laboratories (IREQ) and simulated strikes in outdoor areas (Singapore).
3. What ongoing maintenance does it require?
Down conductors and earths are usually tested annually. The Pulsar air terminal requires a quick and simple test of internal components every 3 years. This is carried out with a test unit. For tricky situations and risky manipulations at height, a telescopic pole can be used. Once a good contact is made between pulsar and pole, the bottom of the pole is connected to the test unit. A second cable at the base of the test unit is connected to a down conductor. The high voltage cylindrical body of the Pulsar is activated and the signal collected by the test unit. This ensures the performance of the Pulsar.
At the end of the manufacturing process, each Pulsar is subjected to a voltage test, to check that their internal insulation voltage is higher than the breakdown voltage of the air terminal. A second current test checks that lightning will be directed to earth. A further test checks the characteristics of the high voltage signal (frequency and amplitude) this ensures the good operation of the pulsar.
As less conductors and earths are tested, the annual maintenance is cheaper than that of a Faraday Cage type system.
4. Does it incur running costs?
No, the Pulsar is a self contained, autonomous unit. It gains the power it requires from the natural build up in electric field. (See above for operating principle). When there is no rise in field level the pulsar is inactive.
5. Where has the pulsar been fitted?
There are over 2000 units protecting buildings in U.K. (Worldwide – 250,000) of particular interest may be clients such as The Ministry of Defence, Home Office, Foreign Office and the RAF, Pulsar systems have been adopted by Thames Valley Police, the NHS, and private and public Consultants alike. Sensitive area such as airport control towers (B’ham International) and satellite equipment (Marconi, Siemen Plessy, NTL) have been protected. Historic buildings such as The Royal Albert Hall and The Victoria and Albert Museum are protected. Clients even include Insurance companies such as Royal Sun Alliance.
6. Does this design meet the standards required under BS EN 62305?
The Helita Pulsar system meets requirements of French National Standard NF C 17-102. The present position with BSEN 62305 is that no more work is to be carried out and standards concerning lightning protection will now be handled at a European level under the new code ENV 61024. Although too early to verify, the NF C 17-102 in all probability will be re-prefixed with CEN or ENV or similar. ENV 61024 will consist of series 1 (National standards adopted) and series 2 (corresponding risk assessments for different European Countries) from a legal perspective, the Pulsar in terms of BSI Test Report 227/5069 is legally honoured, and in itself, a due diligence defence in a court of law.
7. How do I know where to locate the air terminal?
The Pulsar is located at the highest point of the building, utilising and ‘elevation’ above the main roof area as a mounting position (i.e. chimney, lift shaft). A central position is preferable. From the proposed location of the Pulsar, it is necessary to determine the furthest point of the building to be protected. This figure (in metres) represents the Radius of Protection (Rp) that the Pulsar must achieve in order to provide comprehensive protection to the building. This is calculated according to standard NF C 17 – 102, and is in fact the same mathematical modelling that is used in BS EN 62305.
If the building is particularly large, it may be necessary to use more than 1 Pulsar. For example, Olympia Exhibition Centre is protected by 6 Pulsars. It was necessary to ensure and overlap of the radius of protection provided by each unit.
8. How many conductors are needed to complete the system?
Each Pulsar is to be installed with 2 No. conductors, each terminating in an earth pit. The collective Ohms reading is 10 or less.
Lightning Protection
An update on standards and industry news.
As BS 6651 (1999) has been withdrawn the new code for lightning protection standards is BS EN 62305 part 1-4 The position can be summarised as followed:
1. BS 6651 code of practice for the installation of a Faraday Cage has been withdrawn. It will become integrated into a European standard BS EN 62305 parts 1 - 4
2. According to a policy statement at The Office of Fait Trading (OFT) systems should be installed according to a recognised standard of a member State of Europe. Therefore, clients have a choice of early streamer emission systems or Faraday Cage systems.
3. Future standards will be referenced CENELEC.
4. BSI Test Report 227/5069 (1999) ‘Certificate of test witnessing’ for the Helita Pulsar Early Steamer Emission system is independent from BS EN 62305 and not subject to future withdrawal. A BSI Teat Report is a due diligence defence in a court of law.
5. ESE systems protect prestigious buildings throughout the U.K including: The Building Research Establishment, The Royal Albert Hall, Westminster Central Hall, Embassy buildings, NHS Hospitals and household of The Royal Family.
The system has recently been accepted by the Home Office, and protects a prison in London. The system had been adopted by Thames Valley Police for the protection of Police stations and premises.
Pulsar Lightning Protection System - General
A complete lightning protection installation shall be in accordance with French Standard NF 17-102. The installation shall be in accordance with BS EN 62305 as far as it is deemed necessary. The nature and performance of the air termination system alleviates the necessity to comply with all recommendations of BS EN 62305.
The installations shall comprise an air termination system, down conductors, test points and earth terminations. The installation shall be supplied, installed and tested by a lightning specialist sub-contractor. The materials and components shall comply with the relevant sections of this specification. Air termination systems shall be installed at the highest point (quantity as required) of the structure to be protected.
The Helita Pulsar air terminal is deemed acceptable by virtue of BS Test Witnessing Report number 227/005069. The air terminal (s) is to be installed so as to provide comprehensive protection to the structure. This calculation must consider the height of the pulsar tip over the area to be protected (minimum height = 2m. The air termination must be located 2m higher than any roof plant/aerial clusters) the risk assessment follows BS EN 62305. Each air termination system shall be fitted with a minimum of 2 No. Down conductors.
Down Conductors
Down conductors shall be fitted at positions as required, PVC sheathing is to be installed to the conductors, a minimum of 2 no. down conductors shall be fitted with each air termination system. Each conductor shall be a 25mm x 3mm aluminium or copper tape PVC covered securely fixed to the structure of the building by purpose made clips.Test Point
A test point, fitted at approximately 500-600mm from ground level, shall be provided on each down conductor. The test point shall be suitable for isolating the earth terminations for testing purposes. The test point may be formed by a bi-matallic connector link.Copper Tape
PVC covered copper tape shall be run from the test point to the earth electrodes. The tape shall be 25mm x 3mm cross section.Electrolytic Action
Precaution shall be taken to prevent electolytic action of dissimilar metals. The specified method of hygroscopically jointing the tapes shall be adopted, care taken to ensure that all moisture is expelled before making off the joint.Earth Electrode Housing
An earth electrode housing and inspection pit shall be supplied and installed by the contractor. It shall be fitted with a cover and words ‘earth pit’ cast in the concrete or engraved in the cover plated material.Roof Upstand
Where tapes enter the building through the roof structure a non-conducting and non-combustible sleeve, suitably sealed shall be installed.Bonding
As the air termination system provides an ‘umbrella’ of protection, under which all structures remain protected, the need for bonding is kept to a minimum.1. All metallic structures located within 1m of down conductors requires a bond by means of aluminium tape 25mm x 3mm.
2. Where two or more terminals are located on the same structure, a bond between the two is necessary where practical. Aluminium tape 25mm x 3mm is suitable.