LEM's new transducer series comprises three models: ITC 1000-S, 2000-S, and 4000-S, with corresponding nominal current measurement ranges of 1000, 2000, and 4000 ARMS. LEM specifically designed the ITC series for the railway industry, achieving Class 0.5R measurement accuracy when Class 1R is required according to the prEN 50463 standard for on-board energy monitoring. The ITC series features a linearity error of less than 0.05% with offset currents below +/- 20 µA.
The rail traction industry demands unprecedented accuracy, necessary for maintaining optimal control of traction motors, but primarily for energy measurement to record energy consumption for tax purposes, such as billing for electricity costs on trains crossing regional borders. The industry is working on a provisional standard (“pr”) called prEN 50463.
Accurate energy measurement depends on precise current and voltage measurements, and LEM has a comprehensive offering for prEN 50463. The ITC series transducers, along with high-precision voltage transducers such as LEM’s DV series (available with certified Class 1R or Class 0.75R accuracy), and an energy meter like LEM’s EM4T, provide the required level of accuracy.
LEM's measurement experts determined that Hall effect-based measurement techniques could not provide the necessary accuracy. Therefore, they applied their expertise to closed-loop magnetic induction, resulting in a design with excellent levels of accuracy and linearity, low thermal drift, and the elimination of insertion losses. The ITC transducers are insensitive to the primary conductor's position within their large measurement aperture, offer an insulation test voltage of up to 14 kVRMS/50 Hz/1 min, and exhibit excellent immunity to transient overloads (100 kA for 100 ms) and external interference (such as the magnetic fields common in railway environments).
Current consumption ranges from less than 80 mA to less than +/-340 mA for the measurement range with a +/-24 VDC power supply. The bandwidth for the ITC 4000-S is 82 kHz (3 dB), and the transducer openings allow for the insertion of large conductors: 102 mm in diameter (for the ITC 4000-S) or 63 mm in diameter (for the ITC 2000-S). A test winding allows for easy verification of the ITC transducers' operation without current flow in the primary.
LEM offers the ITC series in a one-piece package (model ITC 4000-S) or in a split construction (models ITC 1000 and 2000-S) with the measuring head in one capsule and the measuring circuitry mounted remotely in a metal housing in order to facilitate the placement of the measuring head in restricted spaces such as the roof of the train.
ITC transducers operate within a range of -40 to +85°C and meet or exceed all reference standards for safety and the railway environment, such as EN 50124-1 and EN 50155.
Their high accuracy also makes ITC transducers ideal for a wide variety of differential current measurement applications requiring 0.5% accuracy within a nominal current range of 5 to 150%.
