Intrinsic safety: сompetitive Russian market.
Minimum risk. Maximum efficiency.
The technology of intrinsic safety provides for an acceptable level of safety in all areas. It is possible to assert that such a method of protection means more safety and is less prone to random errors as compared with other methods. So, alongside with flexible application of available apparatus and a possibility of live maintenance of equipment, the technology of intrinsic safety is a natural choice for measurement systems in hazardous areas. In particular, this is the only technique fully applicable in Zone 0.
An intrinsically safe circuit is a commonly accepted method of explosion protection, and intrinsically safe barriers make connection of instrument loops safe both in standard operational conditions, and in emergency situations. Safety barriers are based on the principle of limiting the amount of energy allowed to pass between safe and hazardous areas to a level that cannot ignite flammable atmospheres. The development of automation systems, advancements in technical solutions, an increasing range of various communication protocols have brought forward wider functional capabilities of interface units as well. As an example, an intrinsically safe barrier being just a passive device providing for intrinsically safe parameters of electrical loops, has taken over the functions of power supply, metering and input signals conditioning into the standard output format. Apart from this, galvanic isolation of all the loops is ensured (input loops from output and power supply loops) providing for higher signal noise resistance. The devices are known as ‘active barriers with galvanic isolation’.
Solution of the technical task.
For an intrinsically safe barrier it must be reliability. This is why operators act rather conservatively when making a choice of intrinsically safe barriers, often preferring known reputable brands. Such a choice is re-confirmed by the position of manufacturers themselves, let us take Eaton Electric ltd. (MTL), which has been working in the Russian market for over 20 years. Though it does not mean that home producers of intrinsically safe equipment are in a weak position. On the contrary, a tendency for import substitution which is characteristic of instrument engineering on the whole, or to some extent forced by the situation, defines high level of competition in the market.
To provide for intrinsic safety the user may resort to Zener barriers or barriers with galvanic isolation by western manufacturers as well as to those manufactured locally.
The list could go on… Industry operators dealing with processes potentially hazardous in terms of explosion protection are cautiously optimistic when considering a possibility to choose safety barriers based on a wide product line available in the market today. There is no need to comment on suppliers offering «a quick search of a product-substitute» or «a substitute of imported solution»? In fact, there is often a substitute of notions in place.
One has to take into account the fact that electronic components of intrinsically safe modules are still being mostly imported, not withstanding the development of electronical industry in the country. This, depending on the source, may influence substantially the quality of products. So, import substitution as a concept is not always possible and feasible either.
Optimization and specialization.
With a wide product line, it is highly important to offer the user a solution for a concrete task not compromising on the accuracy of a transferred signal.
One of the parameters defining metrological characteristics of a barrier is its transfer impedance. Reducing transfer impedance provides for wider application capabilities, as it is possible to use sensors of various physical parameters with higher lower limit of supply voltage, and, hence to increase the value of resistance of a useful load.
MTL offers to the user a wide choice of barriers with galvanic isolation for a backplane and a DIN-rail mounting in line with state-of-the-art requirements for system interfaces. DIN-rail mounted barriers provide for a wide range of functions with high accuracy and reliability, and backplane mounted modules as IS system interfaces offer solutions for all major DCS companies.
An innovative planar technology, which is used in components for barriers with galvanic isolation series, has made it possible for MTL4500 and MTL5500 to improve efficiency and provide for easy operation of DCS including functional safety management as well.
At the same time it is important to allow for barriers application at various technological processes keeping in mind operational temperature range. Having said that, some Russian manufacturers offer operational temperature range from -50 to +60 °С.
Fight for millimetres.
Small size is a key requirement to barriers. Signal concentration at a modern plant is so high that mounting density in cubicles sets its own requirements to barriers specification.
As an example, MTL7700 shunt-diode barriers — double-channel or solid-state modules allow for high mounting density — just 6,3 mm per channel. When used with a power bus, minimum cabling is required with a maximum mounting density and the lowest price per channel.
And finally, the price issue which is not explicitly a priority on the list of arguments, but is of principal importance. The price structure is based on a number of factors, and is a complex notion. Anyway, a stated manufacturer’s price for a concrete product serves a starting point for a user decision making process.
In the opinion of specialists, the price for home-manufactured barriers in many cases when compared objectively is close to the price of western manufacturers, biased in one direction or another.