With subsea oil and gas fields having design lives of typically 15 years or more, most of the monitoring technology for line insulation resistance tends to be ‘older generation’ by the time it is really needed to be used. i.e. insulation resistance (IR) problems as a result of water penetration into cables and connectors are more prevalent in later field life. Most of the older generation Line Insulation Monitors (LIMs) were designed for onshore applications and therefore not optimised for monitoring low IR as is typically found in the ageing subsea assets. The challenge presented is to replace low performance LIMs (which have a range of different physical forms and electrical interfaces) with the latest generation V-LIM whilst minimising system downtime during the change-out.
Viper Innovations has designed the V-LIM to allow the unit to be retrofitted into existing systems as easily as possible, without compromising the design. The unit is built into a custom extruded case specifically designed to enable the unit to be installed in place of the Bender IRDH 375, with only minor modifications to the topside controls equipment required.
For older systems that utilise the IRDH 1065, IRDH 1025 and IRDH 1007, Viper Innovations has designed a suite of ‘Interface Modules’ that allow the V-LIM to be easily integrated. These interface modules are fitted in place of the Bender LIM and route the required electrical signals from inside the existing Power Module to front panel connectors.
Once the interface module is installed, the electrical signals can be routed to the V-LIM units. A decision on the mounting arrangement for the V-LIM units can be made on a project-by-project basis and optimised for the specific system. One example is where the wiring from the interface card is routed via harness directly into a separate panel where the V-LIM units are mounted. A second example is where it is possible to make minor modifications to route the wiring harnesses in the rear of the 19” rack.
As well as the higher measured Insulation Resistance (IR) range, the addition of Insulation Capacitance (IC) & Voltage measurement and full data log capability, the upgrade to the V-LIM has also enabled the following advanced functions;