Upgrading Rail Infrastructure with Knick HV-Transducers and Dewesoft DAQ Systems

Metros in large and small cities provide daily rail and bus services to billions of commuters worldwide. Rail service requires monitoring and maintaining hundreds of traction power substations, circuit breakers, transformers, rectifiers, and protective relay devices. The rail infrastructure required many voltages, currents, temperatures, and other parameters to be measured. In the case of one metro, the sheer number of channels was impossible to capture with their existing measuring systems. They searched the market for high-voltage measurement devices and railway data acquisition systems to meet the challenge. Here’s what they found and how it helped them.

The Challenge

The metro must monitor voltage, current, and temperatures at its traction power substations and tiebreaker stations, which include traction power facilities, high-speed circuit breakers, transformers, rectifiers, and protective relay devices. Electric railcar monitoring, voltage and current monitoring, and substation equipment monitoring are interconnected imperatives that require high-isolation DAQ instruments and high-voltage transducers. Metro engineers realized they needed a distributable system capable of monitoring data in a synchronized way, so they conducted a market search to find a solution.

Since the metro’s railcars are electric, monitoring high voltages and currents is essential. This data must be obtained safely, so the hardware requires sufficient electrical isolation. Measurements must also be highly accurate and available quickly. Understanding these electrical quantities as they relate to the performance of the substation equipment is essential.

Potentially dangerous events like short circuits can be identified and dealt with expediently through a transducer’s communication to a protection relay and a high-speed circuit breaker. Safety, speed, and accuracy also play an essential role in recording fast transients seen during various rail system operating conditions.

Transformers and rectifiers convert power from AC grid voltage and apply the power to the rail system. Temperature increases can indicate loose, worn, or failing electrical connections, so monitoring them at key measurement points is essential.

Accurate voltage, current, and temperature monitoring allows the metro to address issues before they interrupt service or cause safety issues. Constant monitoring enables the metro to determine the overall health of the rail lines while providing invaluable historical data to assess the root cause of system anomalies and prevent service interruption by keeping maintenance teams informed of conditions on the line.

Metro engineers studied the market and discovered Knick’s high-isolation transducers and Dewesoft’s Krypton DAQ:

Solution #1: Knick Transducers

The metro’s electrical specifications detail a comprehensive list of performance requirements for transducers. This includes calling for continuous isolation at a minimum of 2.2 kV to withstand permanent voltages and a test voltage of 10 kV for protection against fast transients. To accurately capture transient events, measured values must be linear to at least 200% of the transducer’s nominal range. Related to transmission speed, a 90% input range change must be converted to the output (known as T90) in a time not to exceed 110 microseconds.

Testing data with the Knick P41000 series transducer shows the linearity at twice the nominal range.

The metro selected Knick’s P41000 series current transducers and P42000 series voltage transducers. These models met or exceeded the project’s electrical specifications and have many years of proven performance as transducer standards in challenging rail industry applications.

These devices are compact and are DIN-rail mountable. The input/output settings are flexible, and the universal power supply supports 20 to 253 V AC/DC. Galvanic isolation is provided across the input, output, and power supply (3-port) with continuous voltage protection up to 3600 V AC/DC.

The P41000 measures current via shunt voltage, with a nominal input selected by the metro of ±50 mV. Coupled with a high-performance shunt, this allows currents up to 25 kA DC to be accurately and safely measured.

With the P42000 voltage transducer, the metro intended to monitor a nominal bipolar range of 1000 V DC, with the capability to see disturbances in the system to ±2000 V DC. The benefits of Knick high-voltage transducers in rail systems were immediately apparent, given that they provided data at cutoff frequencies beyond 5 kHz.

Knick’s P41000 and P42000 series high-voltage transducers

Solution #2: KRYPTON

KRYPTON DAQ modules combine IP67, an extreme operating temperature range of -40 to 85°C (-40° to +185 °F), and 100 g shock protection without sacrificing performance. Their compact form factor would make integrating KRYPTON modules into the metro’s instrumentation cabinets fast and easy.

Dewesoft’s KRYPTON DAQ series contains single- and multi-channel modules.

Regarding DAQ performance, KRYPTON modules use 24-bit ADCs with anti-aliasing filtering on each channel. KRYPTON modules provide high precision and bandwidth. Their isolation and industry-standard connectors were also important considerations. KRYPTON modules interconnect via EtherCAT, an interface similar to Ethernet except adapted for DAQ systems to carry power, signal, and timing on a single cable. The EtherCAT protocol provides time synchronization among all modules on the chain.

With its 20 kHz sample rate, the KRYPTON 8xLA module simultaneously provides FFT and harmonic analysis of all analog inputs. These features and the ability to create custom math formulas and filters and calculate real-time statistics make Dewesoft a great solution.

The digital inputs of KRYPTON 16xDI modules monitor and capture the DC relays' digital (on/off) signals. These digital signals trigger recording at the maximum sample rate before and after a breaker trip event to capture transient spikes in high fidelity without missing peaks. These high-speed recordings are critical to determining the root cause of failures while informing metro engineers of solutions to prevent recurrences.

KRYPTONi 8xLA module

KRYPTONi 16xDI module

Conclusion

The metro invested strategically in solutions from Knick and Dewesoft to implement their railway system upgrades. The scaled outputs from the Knick transducers fit perfectly with Dewesoft’s KRYPTON module inputs. These instruments collect and analyze historical and real-time data, empowering Metro engineers to make quicker and better-informed decisions. They can detect and react to unexpected power distribution system failures in real time. The safety of the electric systems and their customers is their paramount concern.

Monitoring and maintaining traction power facilities is a huge challenge. However, combining these solutions with the metro's rail engineering expertise reduced downtime, improved on-time performance, and increased efficiency. These enhancements make for happier commuters.