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An acceptable level of power quality (i.e. voltage quality) is absolutely crucial to the safety and operational integrity of onshore or offshore oilfield installation, irrespective of type.

In order to ensure this, continuous (including trend and event monitoring) of all the salient power quality (PQ) parameters is strongly recommended.

Indeed, continuous monitoring of PQ, especially harmonic voltage levels, may be well be a future mandatory requirement from offshore and marine safety authorities throughout the world who are responsible for fixed and mobile offshore installations in the respective waters (and land, where applicable).

The rationale for continuous power quality monitoring is clear.  As well as satisfying any future regulatory requirements for offshore and marine safety authorities with respect to harmonic voltage distortion levels, continuous monitoring can ensure that any signs of any degradation in power quality are recognized timeously and remedial action taken to resolve matters before equipment is adversely affected leading to disruption in production, equipment failure or worse.  In addition, any ‘events’ (e.g. voltage dips and/or events leading up to, for example, a breaker trip or total blackout of power are captured to assist in any investigations as to the cause).

PQGuard Power Quality Monitors

Due to the reduction of costs of electronic equipment and the considerable advances in software over recent years it is now possible to provide small, but powerful remote (and local) power and power quality measuring/monitoring/reporting systems at relatively low cost to the drilling and offshore sectors such as the Sentinel Power Quality, ‘PQGuard’ monitoring unit.  This low cost PQ monitoring system uses a Microsoft Windows™ internet interface with embedded website (IP addressable which can be accessed remotely anywhere in the World, subject to suitable password and other security controls.

PQGuard can monitor individual installations locally (i.e. onboard) by electricians and other technical staff and/or should a suitable internet connection be available, over the internet by company maintenance departments, fleet managers or third party specialist companies contracted to manage power quality on behalf of the owners and/or operators.  Multiple rigs or oilfields and well sites can also be monitored remotely at one central point, if required.

This type of ‘PQ monitor’ can provide and display power and power quality data locally to single or multiple dedicated stations, can be interfaced with ship, platform or rig supervisory systems and, as are they web based with dedicated IP addresses, can also communicate with any PC (personal computer) connected to the intranet/internet to provide remote monitoring, analysis and reporting anywhere in the World.  They can also be interfaced to DCS (distributed control systems) systems such as Modbus, Profibus and Ethernet.  Instantaneous, trend and event recording is provided.   Panel/switchboard displays and touch panel PCs can also be interfaced.

Single monitoring units can provide an overall power system overview or alternatively, multiple devices, for example to monitor discrete generators, can also be configured and communicated locally and/or remotely within the installation and/or with other offshore or onshore locations.

PQGuard provides continuous monitoring of all power parameters including waveforms and harmonic spectrums :

  • Voltages (line and phase voltages)
  • Total harmonic voltage distortion both including Uthd (line voltages) and Vthd (phase voltages)
  • Currents (A)
  • Current distortion (Ithd)
  • Frequency (Hz)
  • Energy – kW, kVA, kVAr
  • Displacement power factor (DPF) and true power factor (TPF)
  • Harmonic voltages and currents (tables and harmonic spectrums to or 63rd order)
  • Flicker (Pst)
  • Temperature (if PT 100s connected)

PQGuard is local/remote power quality monitoring systems has powerful tools, including the following facilities:

  • Full set of trend recordings for up to one year with date/time playback.  PQGuard provides magnification of parameter display to assist with analysis. The trend recording parameters are updated every second.  The accuracy is based on the sampling rate.
  • Adjustable event recording (e.g. “SCR 1 trip”) with two cycles before and after the event with playback. The limit values of each PQ parameter can be set and alarms initiated if required. On some more advanced monitors, emails can be sent to programmed address(s) to advise and event has occurred.
  • Waveforms of voltage and current for trouble shooting or monitoring.  PQGuard can provide magnification of waveforms and spectrums to assist real time analysis.
  • Harmonic voltage and current spectrums at point of connection to 63rd harmonic. PQGuard allows for waveform magnification for analysis purposes.
  • If additional I/O installed, MCCBs and other equipment can be monitored (on some units).

Remote/local power quality monitoring can provide important information on all the salient power and power quality parameters and may provide prior notice of some impending power or power quality problems.

PQGuard can be connected to either the low voltage (LV) or medium voltage (MV) systems via suitable PTs (‘potential’ or voltage transformers) (PTs) and CTs (current transformers).  PQGuard can communicate directly to a laptop or pc, a local monitoring panel or to the owners or operators office onshore thousands of miles away; or indeed, to a specialist company, contracted to monitor the company’s ships, rigs or platform’s power quality.

For further information of PQGuard please click here – Offshore Marine PQ Monitoring – Salient Features of PQGuard