Signal conditioners rated for SIL2 applications

Edited by the Engineeringtalk editorial team Jan 17, 2007

Trip amplifiers and signal convertors have been assessed and awarded SIL2 rating by an independent safety integrity consultant.

Lee-Dickens, the UK instrumentation manufacturer announce that its range of high quality trip amplifiers and signal convertors have in most cases been assessed and awarded SIL2 rating (with a proof test interval of one year) by the independent safety integrity consultant - RM Consultants.

The continuing drive to improve the performance, reliability and standardisation of safety systems led to the IEC61508 standard (Functional safety of electrical/electronic/programmable electronic safety related systems), which defines safety integrity levels (SIL) as measures of the safety of a given process.

The Lee-Dickens range including BD100, BD120, BM100, BM120, BD300, BM303, BM916, BD320 and BM320 products feature "excellent circuit design" that enables them to achieve the SIL2 classification where some comparable products on the market only manage SIL1.

In addition the Lee-Dickens products are all non-processor-based, which is especially important to industries such as oil and gas, nuclear power generation and steel.

These same industries are also now demanding that instrumentation being implemented into new installations achieve a rating of at least SIL2 or preferably higher.

Signal convertors currently on the market largely fail to meet these demands, so the Lee-Dickens range become increasingly desirable especially as they remain price competitive.

The BD100 and BM100 are single level trip amplifiers and the BD120 and BM120 are dual level trip amplifiers, each from a single process signal input.

The BD300 and BM303 are isolating signal convertors, which will convert a range of process signals into standard transmission voltage or current signals.

The BD320 are BM320 are also isolating signal convertors, which convert process signals into two independently isolated current or voltage outputs.

Finally the BM916 is a low input impedance isolating signal convertor suitable for conversion of a milliamp signal into an isolated current or voltage output where minimal input loop resistance is important.

Safety integrity levels refer specifically to the probability of failure on demand (PFD) - or to what extent the end user can expect his process to perform safely, and in the case of failure, fail in a safe manner.

By selecting devices that are rated for use within a desired SIL environment, end users can optimise their processes for risk.

The advantage for end users selecting a product with a SIL rating and accompanying assessment summary is that reliability calculations are already performed and available to the end user.

The user also has the security of knowing that a third party has reviewed the reliability statistics for the product, and most importantly the attached certification report that accompanies each product contains important information ranging from restrictions of use to diagnostics within the device and also reliability statistics.