The power supply on board ships appears to be standardized around 600VAC 60Hz 3-phase floating (not referenced to ground) with transformers used to provide 400 and 230V delta circuits where required.
The Reliable Power Meters' Power Recorder (PR) can be set to monitor 3-phase circuits in both star and delta modes. As the standard ship system is the latter the PR will work perfectly. When in delta mode the N and G inputs are disabled (as they are not required) therefore do not need to be connected.
If imbalance caused by unequal leakage currents is of concern, then use the instrument in 'star' (wye) mode and connect the N and G inputs to earth. Any imbalance of the derived Neutral will be shown in the appropriate graph.
The recorders are capable of up to 707V input. Connection to a 600V system leaves sufficient headroom (+18%) to measure any reasonable overvoltage. If the instrument is coupled to higher voltages then connection through VTs (or other means of extending the input range) may be necessary.
The recorder is also capable of 60Hz ±3Hz. Please ensure the recorder is setup correctly, this must be done at the first linking to the recorder as the frequency selection is greyed out from that point on. Not having the system set to the correct frequency will null and void all harmonic recordings.
The power for the recorder may be derived from any 115V or 230V phase-phase voltage. Please do not be fooled by using a 400V circuit phase to ground (400÷1.73=230). This could have protection systems tripping as they would see an imbalance or residual/ground current.
Note: It is imperative that the instrument is earthed through the mains input plug (the 'G' input is not the instrument earth). Failure to do so could lead to strange measurements.
If there are any questions please ask.
Note: This web page does not form part of any official documentation.
© M.T.P. - 10.10.02