Motors and Drives
“It created black-outs, which our customer regularly experienced, with the possibility of adversely affecting passengers’ safety and comfort,” Orfino explained. “Another difficult challenge was integrating a new control system into an existing and functioning shipboard’s electrical system. “We suggested that the customer upgrade a star delta
starting system with a new 37kW 220V AC Allen-Bradley drive to handle a peak of at least 10 times the rated motor current. In this way, it has been possible to keep only one generator in service instead of the two previously connected in parallel to the shipboard utilities and air conditioning system.”
Data Centres
Traditional data centres use computer room air conditioning/ handling (CRAC/CRAH) units from various manufacturers with air distributed under floor via vented tiles. Outdoor heat rejection is via dry cooler, condenser or cooling tower typically used in over 90 per cent of installed data centres and still used in over 80 per cent of new data centres.
In certain climates, cooling systems can save over 70 per cent in annual energy costs by operating in ‘economizer’ mode, corresponding to a reduction of over 15 per cent in annualised power usage effectiveness (PUE), according to Schneider APC. Operating in economizer mode saves energy by utilising outdoor air during colder months of the year allowing refrigerant-based cooling components like chillers and compressors to be shut off or operated at a reduced capacity. Economizer mode allows refrigerant-based mechanical
cooling to serve as the secondary mode of operation or backup. At the DatacenterDynamics London conference in December 2011, Paul-François Cattier, VP for data centre solutions at Schneider APC, said: “The concept of a bypass of the compressor function is central to all economizer modes. Historically, building an economizer mode into a data centre cooling system was only justified in situations with extremely favourable weather conditions, such as high latitudes. “However, economizer modes are now considered
advantageous in almost all locations because data centres spend considerable time operating at light load. An economizer mode must take advantage of a wide range of outdoor conditions in order to maximise the number of economizer mode hours and save energy. However, in periods of extremely hot outdoor conditions, it is necessary to at least partially depend on a refrigerant-based mechanical cooling to reliably maintain data centre environmental conditions while saving energy.” However, the transition between economizer mode and
refrigerant-based mode can be very complicated and could result in a temporary loss of cooling during the transition, warned Cattier. Air conditioner bypass via air heat exchanger or via heat wheel economiser modes have the simplest control systems. The most complex economizer mode control system is
Fig. 3. Paul-François Cattier, of Schneider APC, says: “Historically, economizer mode was only justified in favourable weather conditions, such as high latitudes.”
the chiller bypass via heat exchanger due to the dead band between the low condenser water temperature required by the plate-and-frame heat exchanger and the higher condenser water temperature required by the chiller. ●
Precision involute spline shafts O
ndrives Ltd has recently launched a range of precision involute spline shafts and bearing shafts into
their most recent gear products catalogue for 2012. These parts are made in-house by
Ondrives at its state-of-the-art CNC manufacturing facility in the UK. This means Ondrives have a lot of
control over the quality of the products produced, due to heavy investment in the latest CNC technology and machinery. This all goes hand in hand with four dedicated CAD seats producing drawings to the highest standards using the Kissoft range of gear software to calculate the programmes. Spline bushes are also included within the range to suit the spline shafts as well
50
www.engineerlive.com
as spline shaft clamps. The main benefit of using Ondrives’
spline shafts and associated parts within a customer’s application is as connecting elements for drive systems but at a high
level where precision is key, says Managing Director Andy Higgs. They are produced and made to DIN5480 W 8f slide fit in both steel and stainless, for those applications that require it, continues Chairman Ben Hinchliffe. Sizes start at 1.25 Module, going to 2.00
as standard but other modules as well as numbers of teeth, tolerances and materials are all available on request. Specials and modifications are easily catered for as this is one of the main parts of Ondrives’ business in this highly competitive market. ●
Enter 50 or ✔ at
www.engineerlive.com/ede
Ondrives Ltd is based in Chesterfield, Derbyshire,
UK.www.ondrives.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68