Setting of the required load resistance uses an HMI which selects a combination of 20 off-load switches. Additionally the settings and test parameters can be monitored and recorded on the data logging system.
Type EN650/strip traction resistor elements, arranged in individually replaceable banks 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 Alloy 601, a 60:23 nickel-chrome stainless steel. This is a high grade stainless steel with excellent corrosion resistance properties and a low (0.012%/°C) temperature coefficient of resistance, giving very stable resistance values over the whole range of operation.
The off-load switches allow for the reconnection of the resistors in each stack into more than 200 different configurations with a range from .026 Ohm/7000A through to 3.3 Ohm/600A. There are intermediate points to suit the majority of loco alternators up to 4000hp rating.
The load consists of twin fan-cooled resistor ducts with fans, starters and controls, two main load isolating contactors and an integrated HMI/off-load switch panel permitting the pre-selection of any one of more than 200 values of resistance between 0.026 Ohm and 3.3 Ohm. 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 coat. The enclosure is designed for floor mounting with bottom cable entry. Fan motor and control voltages are set to suit the user’s own available supply voltage and frequency.