Continuous Power Quality Monitoring

Power quality is extremely important due of the increasing complexity, size and interconnection of electrical networks and their non-linear drive loads are/will be connected to.  In addition, it gives crucial information on the connected loads and processes, including prior warning of harmonics and PQ problems such as the impending failure of diode in one phase of large 6 pulse VFD and energy.

Impending diode breakdown at input of 2100kW VFD input

To connect to utilities, legal contracts must be signed with the consumer which requires compliance with local PQ rules and international standards, for example the current IEEE 519. The salient PQ requirements include THDu, THDi and DFP (displacement power factor – not PQ). However, the utility has also a responsibility to consumers to provide an acceptable level of PQ, usually under, EN60150, “EU Product Standard for Voltage Supplied by Public Utilities”.

Combination of 33kV and DC trends from mass transit system
Line and common mode voltage plus 3rd and 21st harmonic voltage on process line
Large healthcare facility – Active filter ON, then OFF. Interaction with EMC capacitors

It must be stated that continuous PQ monitoring is essential to monitor the utility supply to the consumer AND to ensure compliance with their rules and regulations, which if non-compliant can result in penalties and/or disconnection. The data captured is crucial in the event is disputes with the utility. Any disturbances from the utility can have a serious impact on the oilfield equipment, downtime and associated costs.

Sentinel Power Quality Group can provide continuous conventional and advanced cycle by cycle PQ monitoring.

Example of conventional PQ monitoring for a six-generator power system
SLD of PQ monitoring six generator power system
Sample of active power (kW) and reactive trend for one (of six) generators

Sentinel Power Quality Group can offer the PQGuard 4430 advanced ‘cycle by cycle’ power quality recorder which, when combined with dedicated power quality analytic software, provides unarguably the world’s finest harmonics, power quality and events monitoring system. The PQ recorder can accommodate current signals 1A to 5A per phase from conventional current transformers.

Every single cycle of voltage and current are recorded plus almost 5,000 power and PQ parameters. Harmonic voltages to the 511th and harmonic currents up to the 256th are captured. No event is missed.

PQGuard G4400 cycle by cycle PQ recorder for fixed installations

Features of PQGuard 4430 include :

  • Sampling : 1024 samples/cycle
  • Automatically capture evert cycle and over 5000 power and PQ parameters
  • Harmonics & Interharmonics : Up to 511th voltage/256th current
  • Internal memory : 16GB
  • Transient detection : 19.5/16.3μs (50Hz/60Hz)
  • Ethernet ports : 2
  • Digital I/O : 8 in, 4 out
  • Ride through power loss : Up to 25 secs
  • Voltage channels : 4 off plus ground, 1000V rms continuously (8kV peak)
  • Current channels : Up to 5 off, up to 5A (50A peak)
  • Fundamental frequency : 42.5Hz to 69Hz
  • Power supply : 110-260VAC and 100-300VDC, 48 VDC auxiliary
  • Power over the Ethernet
  • Built-in web server
  • Operational ambient : -20 deg to 70 deg C

An example of sample measurements from the G4500 (portable version) and G4400 (fixed version) illustrate the advanced analysis and troubleshooting possible with these types of PQ monitoring devices.

Min/max and average active power (MW), THDu and THDi 11 days. Note peak THDu of 10.58%. Scaling is 24hrs per division.
THDu peak of 10.58%. Scaling is 20mins per division.
Cause of peak THDu 0f 10.58% ? Two phases contaminated by 1.26kHz common mode voltage from 10,000kW of VFDs. Scaling is 20 milli-secs per division.

Note : Without this type of PQ recorder and deep analysis software, many problems, including those pertaining to safety !

Samples of typical parameter trees, using InvestigatorTM software is shown.

Examples of partial parameter trees for PQGuard 4430 cycle by cycle recorder

Contract PQ Monitoring

Whatever the type of PQGuard system required to be installed, Sentinel Power Quality Group can offer contract remote PQ monitoring. Let us take the full technical responsibility from your company by continuously monitoring, analysing and reporting on your installation’s harmonics and power quality, whatever the application.

This service can also entail detailed weekly, monthly or annual PQ audits, if applicable.