HEALTH & SAFETY PLANNING FOR THE UNPLANNED
HOUGHTON INTERNATIONAL
The importance of a planned preventative maintenance strategy
National Grid operates a Liquid Natural Gas ( LNG ) terminal at the Isle of Grain in Kent , the largest LNG facility in Europe with a throughput capacity of 15 million tonnes per year . Given the critical nature of operations at the facility , stringent safety controls must be followed and a planned preventative maintenance strategy is crucial to the functioning of the terminal . To ensure the strategy was implemented in an effective way , electro mechanical specialist Houghton International was called to assist .
The LNG facility operates a series of 6.6kV blower motors . Since the plant provides essential services , it is crucial to minimise unplanned downtime for all assets and carry out maintenance during planned intervals . Houghton International was contracted by National Grid to carry out periodic testing on a number of motors at the facility . The condition monitoring regime assessed the quality of the HV insulation and the dielectric properties of the motor windings .
THE IMPORTANCE OF TESTING
Houghton International ’ s site services team managed the whole process of testing , decommissioning , removal , transportation , overhaul or rewind , reinstallation and recommissioning at Grain LNG , making operations simpler and smoother for National Grid .
During periodic site visits , engineers from Houghton International carried out tests on the high voltage motors to monitor and log the condition of the electrical insulation of each asset . The engineers used the data as a trending measure to identify motors showing high levels of Partial Discharge ( PD ) or other signs of insulation material deterioration or aging .
The test regime consisted of PD testing and a range of high voltage Baker tests , such as the low resistance and impedance testing , Insulation Resistance ( IR ), HiPot test and the surge interturn test . Collectively , these tests can identify a range of insulation and winding issues , both turn-to-turn and phaseto-phase , providing a thorough assessment of the motor ’ s condition .
A well-planned preventative maintenance strategy is key to the dependable , longlife operation of electric motors .
Reports conducted by Houghton International gave National Grid a clear pass or fail indicator for each test . Further analysis of each motor highlighted recommendations for ongoing monitoring and suggestions for when the motor should be tested again , allowing LNG to establish a clear testing and maintenance schedule . Where results showed signs of insulation aging or deterioration , the reports included recommendations for overhaul .
These overhauls , which ranged from minor maintenance to full rewinds , were carried out in Houghton International ’ s 120,000 square foot facility in Newcastle-upon-Tyne .
Rewinds were completed using Houghton International ’ s HiFLEX coils , which are manufactured in-house by Houghton International . This gives the company full confidence that it can deliver a quality
product within the lead time specified . Houghton ’ s coils also offer better windability , more protection from moisture and contaminants , and reduced Partial Discharge . In one recent rewind , the motor ’ s Partial Discharge reading was independently verified , demonstrating a reduction in PD from 5041pC to 220pC ( Pico Coulombs ).
THE RESULT
By carrying out regular testing , Houghton International could identify which motors were deteriorating , allowing LNG to carry out any necessary repairs before this led to an unanticipated failure .
“ At Houghton International we believe a periodic testing regime is important for all industries but especially those that perform critical operations ,” commented Chris Measor , Winding Assistant Manager of Houghton International . “ A well-planned preventative maintenance strategy is key to the dependable , long-life operation of electric motors . This is why we continuously invest in the latest equipment to provide a comprehensive range of testing , repair and maintenance services for our customers .”
“ Without the testing regime implemented by Houghton International , several of our critical motors could have failed in service , leading to large commercial costs for the terminal ,” explained Ashley Smith , LNG Terminal electrical engineer .
To find out more about Houghton International and our services , go to www . houghton-international . com .
86 PECM Issue 56