Electromagnetic pulses and electromagnetic interference or electrical noise are a key concern aboard naval ships. Roxtec’s pioneering safety seals are gaining attention in the naval industry for their ability to help withstand EMI more effectively than any other seal presently on the market – it works for both conventional shielded cables and fibre optic cables.
EMI is a prime issue because of the highly sensitive and advanced nature of the technology onboard naval ships which means a higher risk of problems caused by EMI.
Background
Electromagnetic compatibility
EMC is the ability of electrical or electronic devices to function properly in their intended electromagnetic environment, without introducing unwanted electromagnetic disturbance. EMC is a measure of quality and the margins for immunity and emission. It tells how well a device cooperates with other devices, electrically. Several international standards define aspects of EMC.
Electromagnetic disturbances and interference
Electromagnetic disturbances can be caused by various natural phenomena such as sun storms or northern lights. Cell phones and everyday electronics can also affect sensitive electronic equipment in a negative way, and vice versa. There are also undesired electromagnetic fields which can be the result of discharge of static electricity, sparks from switches, electronic warfare or acts of terrorism. If the disturbance is powerful enough to cause a negative impact on the system performance, it is called EMI.
Solutions for naval vessels
With proven products for electromagnetic shielding, you can minimize the risk of malfunctions and failures on a naval vessel.
Using the Roxtec ES sealing solution ensures naval ships can protect against both EMP and EMI. The system is approved by all major classification societies. Roxtec ES seals provide electromagnetic shielding as well as certified protection against fire, gas and water.
Areas of naval vessels where Roxtec cable transits are installed include the command control room, where it ensures electromagnetic shielding and protection of equipment. The compact, area efficient seals further ensure EMP/EMI protection of cabinets and enclosures and make it possible to reduce the size of cabinets, junction boxes and other enclosures as well as to reduce engineering hours spent on cable data and cable gland configurations. Roxtec seals are also used in the communication area of navy ships covering crypto and sonar, where Roxtec cable and pipe transits ensure electromagnetic shielding both inside, and around the rooms. The Roxtec ES solutions work by protecting equipment and creating an internal barrier for sensitive information.
Roxtec Technical Product Manager and Electromagnetic Specialist Mr Mikael Grudd explained the primary purposes of shielding.
“Our shielding solution is concerned with two prime areas,” he said. “First you want to reduce the self-generated electromagnetic noise. There could be several reasons but minimizing the ship’s signature is essential. Also, for signal intelligence ships it is very important as they are listening to signals far away and you need to be able to differentiate them from the background noise. Therefore, your own disturbances must be kept to a minimum which Roxtec seals do.
“Secondly, you want to ensure your sensitive electronics are not disturbed or in worst case permanently destroyed. This would be catastrophic for the ship’s ability to operate and defend itself. So say in the instance of an electromagnetic weapon or nuclear explosion, you do not want your control systems to go down with a very strong EMI pulse. In this instance the energy level is so high the circuits will be permanently destroyed. How do you protect from this? We encapsulate the electronics in a shielded area with a metallic or highly electrically conductive barrier surrounding it on all sides. To be able to access the electronics on the inside, cables and pipes need to be routed through the barrier requiring an opening. The opening is a puncturing of the electromagnetic barrier and weakens the protection if left unattended. Using a Roxtec ES solution, the barrier is recreated by the built-in electrically conductive rubber barrier inside the sealing solution. Key is ensuring the cables do not act as an antenna for EMI and make the situation worse. The Roxtec ES sealing solution restores the electromagnetic protection and allows at the same time cables and pipes to be routed for power, signals and cooling. Roxtec ES solutions efficiently divert disturbances from the shielded cables and via the built-in electric barrier within our modules they also prevent radiated disturbance.
“We want to make the cables and pipes a part of the wall, electrically speaking. We replace metal removed from the wall inside with our solution, effectively repairing the wall. We route cables through the barrier but maintain its electromagnetic performance. This ensures the ship’s electrics do not malfunction and continue to perform all their vital roles powering equipment.”
Mr Grudd said the shielding works by reducing electromagnetic signals and blocking the field with barriers made of electrically conductive or magnetic materials.
“Shielding also works the other way round,” he said. “It prevents electromagnetic signals and fields from leaving a shielded area. You can protect sensitive information from wiretapping or keep disturbances generated by power generation inside a shielded area to ensure emission limits.
“All electrical and electronic equipment are sources of electromagnetic disturbance, which means they have the potential to cause problems in other devices. They can also be affected by electrical interference, which means they are receptors as well.”
Common sources
- Radio, TV and radar equipment
- Electric power lines
- Electronic circuits
- Light dimmers
- Arc welders
- Electric motors
- Electric storms and large solar flames
- Electromagnetic pulse weapons
Receptors (potential victims)
- Radio and TV receivers
- Appliances
- Computers
- Electronics
Eliminate the coupling paths
- Sources and receptors are no problem as long as they are not electrically connected. You can achieve protection against electromagnetic threats through elimination of the coupling path, which is the connection that transfers the disturbance from the source to the receptor/victim.
- The Roxtec ES system provides an effective protection when used in shielded environments. The system both diverts conducted disturbances and shields against radiated disturbances.
- Conducted coupling path – the electromagnetic disturbance travels via cables shields and metallic pipes. The coupling path could be either inductive magnetic coupling or capacitive electrical coupling.
- Radiated coupling path – the electromagnetic disturbance travels via air as an electromagnetic wave. Its energy is absorbed and generates a current flow in the receiving cable/pipe or directly in the electronics.
Mr Grudd continued: “At the Roxtec electromagnetic test lab, engineers and technicians use shielded rooms, antennas, transmitters and receivers to verify the ability of the seals regarding the reduction of the electrical field strength, known as attenuation, of radiated interferences. The shielding performance can be evaluated in a frequency range covering even the toughest requirements. Roxtec ES modules have a conductive rubber layer that attenuates electromagnetic disturbances and forms an efficient barrier against radiated EMI.
“The attenuation level of the seals is presented for easy evaluation and comparison for use in the product development process. The results clearly present the shielding performance of the seals when it comes to protecting the point of entry and forming a complete shielded solution for naval vessels.”
Fibre optic shielding
Roxtec has recently developed a penetration seal for electromagnetic shielding to be used with non-metallic fibre optic cables, known as the Roxtec Waveguide Seal ES. Fibre optic cables are becoming increasingly common in naval vessels for their efficiency. One single fibre optic strand can carry ten times as much data as an ordinary ethernet cable. In addition, one fibre optic cable can accommodate hundreds of fibre strands and thereby replace thousands of ethernet cables and thereby streamline the installation according to Mr Grudd.
“The more modern the ship, the more fibre optics we see,” he said. “Ship designers want more fibre optics to improve installation time and keep down the ships electromagnetic signature, as fibre optics do not generate any electromagnetic signature.”
The Roxtec Waveguide Seal ES is designed for routing non-metallic fibre optic cables into a shielded enclosure while maintaining the enclosure’s electromagnetic integrity. The waveguide seal protects electronics from electromagnetic threats such as EMP and HEMP (see drop box). The solution offers both environmental protection and electromagnetic shielding in a single seal. It is a high-performance product, based on a waveguide technique, offering minimum 100dB shielding effectiveness.
“Very few ships in the world need this 100dB level which is extremely high so this is exceptionally robust protection,” said Mr Grudd. “In addition, very few of our competitors offer this electromagnetic protection combined with water, gas and fire protection. We have all these features in one seal which no other company presently does. Most other solutions provide protection from fire, gas and water but do not protect fibre optic cable entries from electromagnetic interference. Our lab has proved Roxtec seals provide protection for fibre optic cable entries from water, gas, fire and electromagnetic pulses. This is an industry first.”
HEMP – protecting naval ships’ functionality and operability
HEMP is an immensely powerful well known cold war weapon. HEMP is a high-altitude electromagnetic pulse, created through a nuclear weapon detonation tens of kilometers or more from the surface of the earth. The distance is chosen depending on target area and desired disastrous effect. The effects of a HEMP attack are a total disaster for the electrical power grid and other critical infrastructure. It makes transformers overheat and explode – and can blow away the entire power grid. The electricity supply goes down and all modern electronics, including computers, communication systems and systems in cars and aircraft, in a very vast area risk severe damage in just a few seconds.
“HEMP is being talked about more,” says Mr Grudd. “The war in Ukraine as well as nuclear tests undertaken by North Korea are bringing the HEMP threat into sharper focus. Navies are very interested in how Roxtec can protect their vessels as they want their warships to remain fully functional even if they are located close to the initial attack. The ships may be the last line of defence and are not allowed to fail regardless of the effects of HEMP.”
CASE STUDY
The EMC capability of Roxtec’s transit seals is a crucial consideration onboard four new vessels belonging to the Swedish Coast Guard. Here the seal transits for single and multiple cables and pipes are used to ensure electromagnetic compatibility on the vessels which are carrying sophisticated electronic equipment. The KBV 033 vessels are built to handle oil spill, fire-fighting and search and rescue as well as maritime surveillance, fishing control and environmental protection. The need for safe, reliable and flexible transits is omnipresent.
The German shipyard, P+S, selected Roxtec SRC transits for the vessels. The transits were manufactured with special EMC modules with rounded corners to reduce stress around exposed bulkheads and minimize the risk of damage to the structure. This enables the Roxtec EMC system to protect the radar and antennas on upper deck against electromagnetic interference.
The Roxtec seals’ versatility was a prime factor in Roxtec being specified. As well as providing EMC protection the seals further offer protection against water, gas and fire.
ROXTEC BACKGROUND
Roxtec was founded in Sweden in 1990. It is now the global leader in the manufacture of innovative cable and pipe transit systems, supplying many of the world’s biggest firms. It is active in more than 80 markets with a turnover of more than £198million employing over 800 staff across 28 subsidiaries.
One of Roxtec’s biggest sectors is marine, and the company supplies cable and pipe transits for multiple demands to many of the leading navies around the world.
Roxtec seals are further extensively specified on merchant vessels such as tankers, container and cargo ships, cruise ships and ferries as well as superyachts and OSVs.
Today Roxtec has more than 300 registered product certificates and over 500 registered tests and approvals.
CONTACT
Roxtec LTD
Write: Unit C 1, Waterfold Business Park, Bury BL9 7BQ Lancashire
Call: +44 161 7615280
Email: uk-market@roxtec.com
Visit: www.roxtec.com