Load bank launched for testing diesel-electric locos
03 March 2008
Cressall Resistors has launched an easy-to-use, premium built load bank for performance testing diesel-electric engines and generators of all types up to 4000hp. Designated the DC7000, the new load bank has a capacity of 3100kW and 0-7000A continuously at up to 2000V dc. The unit features PLC controlled resistance adjustments and permits the pre-selection of any one of more than 2000 values of resistance, from 0.026O to 3.3O. The range allows routine maintenance tests to be conducted over the entire power envelope. It is likely to find applications in proving new and re-builds before they are introduced to service.
"The traction market is a very important sector for Cressall Resistors," explained Peter Duncan, a director of the business. "We have more than sixty years experience in this industry as well as the know-how from the resistors businesses acquired by us over the years, including Cutler-Hammer Resistors and Alstom Transit. In a sense, these acquisitions future proof our customers' equipment by ensuring that the components they used originally can still be supplied."
The load consists of twin, 14 section, fan cooled resistor ducts with, starters and controls and an integrated off-load switch panel. The fans, resistors and switchgear are all built in to a single sheet steel frame with hinged lockable access doors, air intake screens and, optionally, hand operated outlet louvres. Paint finish is RAL7032 light grey powder paint and the enclosure is designed for floor mounting with bottom cable entry. Fan motor and control voltages are set to suit the customer's own supply voltage and frequency.
The load bank incorporates EN650 traction resistor elements, arranged in individually replaceable trays with all-welded interconnections. Each bank is contained in a fully insulated duct section with two independent levels of 3kV electrical insulation.
The resistor elements are manufactured from Inco alloy 601, a 60:23 nickel-chrome stainless steel. This is a high grade stainless steel with excellent corrosion resistance properties and a low (0.04%/°C) temperature coefficient of resistance, giving very stable resistance values over the whole range of operation.
Motorised off-load switches allow for the reconnection of the twelve resistors in each stack into more than 2000 different configurations, with a range from .026O/7000A through to 3.25O/6000A. There are intermediate points to suit the majority of locomotive alternators up to 4000HP rating.
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