2750kW Azimuth drive motor started via soft starter
Sentinel Power Quality PQ services include :
- Harmonics and power quality surveys/audits
- Compliance testing against marine classification society rules and recent IACS (UR 24) requirements for vessels with electric propulsion
- Investigations into equipment malfunction/failure
- Monitoring of common mode voltage (due to VFDs) and other EMC issues
- Studies (including harmonic modelling) on harmonics and related topics for marine power systems
- Provision of conventional and cycle by cycle continuous PQ monitoring systems
- Training in harmonics, PQ and related issues
State of the art harmonics, PQ and EMI measuring equipment
We use state of the art, cycle by cycle, Class A (0.1% accuracy) power quality analysers which capture every single cycle of voltage and current and record harmonics to 512th for voltage and 256th for current. Every single PQ event is captured and also 10,000 power and power quality parameters.
G4500 cycle by cycle power quality recorder with dedicated laptop and 200MHz scopemeter with spectrum analyser capability in the foreground
Voltage leads plus 3000A Rogowkski coils for G4500 and 3000A oscilloscope CT connected
Sample measurements from G4500 cycle by cycle PQ recorder….
Urms voltage plus Urms voltage and Irms current waveforms during voltage dip
Irms, reactive power (kVAr) and true power factor )TPF) during period of leading TPF
Relationship between Urms voltage, Irms current, Uthd and common mode voltage (%) during start-up and bypass during soft starting of 2750kW Azimuth motor
Relationship (Phase One) between line voltage, common mode voltage and phase current waveforms on vessel with cycloconverter main propulsion drives
Line harmonic voltage distortion spectrum (%) on vessel with main propulsion drives
Phase harmonic current distortion spectrum (%) on vessel with main propulsion drives
Advanced 200MHz digital storage oscilloscopes with spectrum analyser capability for detailed waveform analysis are used on applications including SCR drive line notching, voltage spikes and common mode voltage/current monitoring. High voltage (2kV) probes and CAT1V 1000V equipment ratings ensures the capability to measure at most demanding applications. For medium voltage systems dedicated VTs and CTs are used.
Special micro fibre probes are used with 200MHz oscilloscopes to measure direct shaft voltages on generators and motors. For large shaft diameters, dedicated Rogowski coils are used for current measurement up to 10MHz).
Sample measurements from 200mHz scopemeter….
1500kW PWM VFD output voltage and current
Line notching on 600kW DC drive
Line voltage due to active harmonic filter
Comparison of line voltage and common mode voltage on 560kW VFD which was not installed in compliance with EMC recommendations
Common mode frequency spectrum (V) associated with 1100kW VFD switching at 2kHz
Common mode voltage and current from 1100kW VFD during one PWM pulse
For common mode and other EMI measurements, portable EMC spectrum analysers (1Hz to 30MHz) are used with differential adaptors and attenuation units for conducted common mode voltage and current measurements. Near field probe kits with antennas for radiated emissions and sophisticated software facilitate detailed reporting.
Once analysis is complete, a comprehensive report is issued at the end of every site visit or on completion of a paper study.
Dedicated Marine Power Quality Engineers
Sentinel Power Quality PQ engineers are fully qualified Electrical Engineers with extensive experience in marine harmonics and power quality. In addition, all engineers have considerable knowledge in other associated electrical disciplines including variable speed drives (AC and DC), generators, motors and other marine electrical equipment.
If you wish information on common marine PQ problems please click here.
Alternatively, please contact Sentinel Power Quality directly if you require our specialist services by clicking here.