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Thursday, December 19, 2013

Wind Generation Power Quality & Interconnect Issues

Wind generation plants are growing at a fast pace. Government assistance in the form of production tax credits, grants for capital investment and other sources of funding are fueling such growth. Howe
ver, concerns remain over the interconnection of such plants to the grid as well as overall power quality characteristics. Dranetz provides ideal various solutions for both temporary monitoring or troubleshooting and fixed systems for continual 7x24 monitoring to capture the dynamics over time and alarm on faults, system dynamic changes and deteriorating conditions.
Wind turbine design has evolved with various types in use. Each type can have different power quality characteristics that relate to the generator type, associated power electronics, collector systems and other aspects. Common problems and design considerations studied are grounding, harmonics, voltage flicker, voltage regulation, reactive power and fault ride through capabilities. Measured values can be evaluated against existing standards and guidelines such as IEEE 519, IEC 61000-4-15/IEEE 1453 and those from the Federal Energy Regulatory Commission (FERC).
Trend of measured 5th harmonic current at a wind plant
Dranetz power quality solutions are ideally suited for wind power applications. Combined with our DranView software, our portable tools such as the PowerXplorer PX5 provide you the state-of-the-art tools for onsite troubleshooting and engineering studies performed by plant manufacturers, owner technicians, service organizations and consultants. For fixed, 7x24 applications our Encore Series provides cost effective continual remote monitoring and alarming in a common web browser environment that helps ensure the system is always operating within design guidelines and that you will be quickly notified should anomalies or failures occur.
- Power Quality Considerations of Wind Power Plants, David Mueller, P.E., 2010 Georgia Tech Fault Disturbance Analysis Conference

Tuesday, November 5, 2013

Demand Response Case Study

Data Center uses Encore to monitor Demand Response Performance
A 1.2M square foot Data Center located in Northern New Jersey was participating in a Demand Response program utilizing their backup generators as the primary means of reducing their 7MW of load. The service provider that they worked with installed telemetry metering from the utilities KYZ pulse output to report the performance to the grid operator. However, the facility director wanted live access to the generators output so that they could measure the performance of the generators and watch loading on each of the four 2.5MW turbines in real-time and historically. And, it had to painlessly integrate into his existing BMS system over an IP backbone.
Backup generators are critical to the operation of a 24x7 facility, downtime is lost revenue and lost customers. A facility operator needs to know what’s happening to his system all the time, and electricity is the main backbone of his entire operation. Let’s face it, no matter how many T1’s are coming in from different carriers and different POP’s, if the electricity goes out everything stops working including communications.

Utilizing the Encore Series ES230 DataNode’s along with their existing Encore Series Software installation, the Facility Director was able to give his BMS team a Modbus map for the instruments which were easily programmed. Because these were backup generators installation was much easier, however they were done sequentially in bypass mode because no one knows if or when the power will go out and the engines would be needed for an emergency. After the installation was complete and the integration into the BMS was done, the facility manager performed a live test and the results were perfect. The facilities network operations center (NOC) was able to read the instantaneous values from the generators from their control room, the ES230’s were also integrated into the existing Encore Series Software system so the facilities engineers also gained that they were able to see all of the instruments remotely when needed.
The graphs below display how easy it is for a user to view their reports on energy usage, demand, and any other electrical parameters recorded in the Encore Series Software from any remote location.

The ES230 DataNode’s are small and easy to install and configurable either at the local display or through the Encore Series Software. These instruments are capable of recording Volts, Amps, kW, kWh, kVA, kVAR, Power Factor, Harmonics, and a variety of other parameters simultaneously. They also have the option of RS232, RS485, or Ethernet communications and support native Modbus protocols. The Encore Series Software is a web enabled application that does not require the installation of any software on a local users computer. The system can be accessed from any web-enabled browser by multiple people simultaneously, and performs a variety of operations, including; data collection, data analysis, reporting, alarming, and remote setup of the equipment. With the Modbus driver installed the software can easily read data from any previously installed instrument that supports the Modbus protocol. Additionally, the software allows for easy expansion, including the addition of Power Quality instruments for more detailed analysis of power anomalies.

Friday, October 11, 2013

Sub-optimal Power Quality Can Cause Sensitive Medical Equipment to Fail

Power Quality has always been a key issue for healthcare facility managers. With the rapid advances in medical technology, hospitals, medical clinics and laboratories increasingly rely on sophisticated electronic devices for diagnosis, treatment and monitoring. This equipment is often interconnected within networks, industrial processes and power infrastructure and can be negatively affected by events that arise both from the supplying power system and aregenerated within the facility.
All of the interconnection of electrical circuits, and the high sensitivity of the equipment in use, demands a high degree of power quality and reliability to prevent disruption of mission-critical operations and procedures. Power quality disturbances can be caused by a range of internal and external phenomena and often re-occur because the location and nature of the event is not well understood or identified.
The Dranetz PowerVisa
While the costs of downtime or failures can result in thousands of dollars per hour, the costs of power and equipment failures in critical patient operations are immeasurable. Power monitoring is key to maximizing uptime and ensuring all power infrastructure is functioning properly.

Friday, September 27, 2013

Manufacturing Process Unexpectedly Halted

This medium-sized manufacturing facility, located in an industrial park that experienced an unexplained shutdown of several adjustable speed drives (ASDs) , wreaking havoc on key process equipment. Each day, at approximately 6 am, the utility-owned PF capacitor kicks on to improve the voltage of inductive loads prevalent in many of the park’s manufacturing facilities. The ASDs are conditioned to anticipate this expected power quality event and are typically able to ride through the problem. So when one of the ASDs closed down and interrupted the continuous stream manufacturing process, the facility manager needed to learn why, correct the problem, and prevent it from happening again.

As you can see from the attached screen capture, a second, unanticipated capacitor switching event occurred shortly after the first. This event was categorized by the Encore Series System Capacitor Switching Answer Module , enabling the facility manager to pinpoint the exact source of the problem. Further analysis showed that the ASD shutdown was the result of an overcurrent trip, which was quickly remedied preventing hours of downtime, at a loss of $10,000/hour.

Friday, September 20, 2013

SecuTest & SecuLife Safety Testers From Gossen Metrawatt

The SecuTest SIII+ and the SecuLife ST are universal test instruments for testing the electrical safety of portable electrical equipment in commercial, residential, and medical applications operating at 120V/60Hz or 230V/50Hz.  The SecuTest SIII+ and SecuLife ST are the same basic instrument, with the SecuLife including standard features specific to medical testing, such as testing up to 10 application parts and test sequences per IEC 60601.  In order to evaluate electrical safety, tests are performed for protective conductor connections, insulation resistance, and leakage current.  Individual tests can be performed manually, or testing can be automated by using built-in test sequences that are in accordance with widely accepted international standards.

In the video below, Dieter Feulner, Product Manager for Gossen Metrawatt,  tests for touch current on a mobile X-ray device.

Friday, September 6, 2013

Dranetz Fall Power Quality Seminars

The first Dranetz Fall Power Quality Seminars have been confirmed and we hope you can attend.

These no-cost educational seminars are held at select cities in the continental US throughout the year. This incredible value is open to anyone interested in Dranetz instruments, and only requires registration to reserve your seat. All power quality seminars are 1/2 day and run from 8:00am to 12:00 noon, and a continental breakfast is included.
To register online CLICK HERE.

The current schedule (with more to follow) is:
October 9, 2013
Mayfield Village, OH

October 22, 2013
Albuquerque, NM

October 23, 2013
Lake Oswego, OR

October 23, 2013
Birmingham, AL

October 24, 2013
Greenwood Village, CO

October 30, 2013
Fort Lauderdale, FL

November 6, 2013
Fargo, ND

November 7, 2013
Bismarck, ND

November 13, 2013
Waltham, MA

General Agenda

  • Introduction to Monitoring
  • What Are We Measuring?
  • Transducer Considerations
  • Introduction to Power
    • Energy and Demand, Power Factor 
    • Real-Apparent-Reactive Power
    • Typical Utility Billing Practices
    • Case Study — determining energy costs
  • Going Beyond Energy and Demand 
    • to Improve Reliability
    • Introduction to Power Quality
    • Impact on Business Productivity
    • Maintenance and Operating Costs
    • Identify Typical Power Quality Events (overview of sags, transients, harmonics, etc.)
  • Q & A: Your Application Questions
Ready to register?  CLICK HERE

Wednesday, September 4, 2013

Automatic Distribution Fault Location Case Study

Consolidated Edison Company of New York is a long time user of Dranetz power quality monitoring systems and sister company Electrotek Concepts software and services. Dranetz Encore Series (61000) and Enhanced Power Quality, EPQ DataNodes) and legacy power quality instruments (8010 PQNode) are deployed throughout their network collecting needed data for PQ assessment. Electrotek’s PQView software, which is seamlessly integrated with the Encore System, provides database management, reporting and advanced statistical analysis. PQView’s Fault Analysis Modules identify and characterize faults, providing location information. Alarms are sent to operators who dispatch crews for repair, reducing the time to locate faults by hours.
The automatic distribution fault location system at the Consolidated Edison Company of New York was first put into use during the spring of 2005. It incorporates power quality monitors, microprocessor relays, database applications, up-to-date distribution circuit models, and geographic information system (GIS) databases in order to provide automatic distribution fault identification and fault location estimation. The system has become an indispensable tool for quickly and accurately identifying the location of faults in the Con Edison network distribution system.
The fault location system uses measurements recorded by Encore Series PQ monitors located in distribution substations. These measurements are downloaded automatically by Encore Series Software which manages the power quality monitoring system. Fault data is automatically acquired by PQView software and stored in its relational database. Calculations on these measurements estimate the reactance from the substation to the fault. The calculations are based on phasor measurements derived from the voltage and current samples and calibration constants based on previous fault data and known locations. The result of these calculations is an estimated “reactance to fault,” or XTF. The XTF values are compared with feeder models that estimate the positive-sequence impedance between substation and feeder structures. The estimated locations can be viewed in tabular format on the corporate intranet and can be displayed graphically using maps derived from a GIS database. The estimations for fault location typically are available on the company intranet approximately ten minutes after the fault’s occurrence. The estimates are accurate to within 10% of the total number of feeder structures, for about 80% of the single-phase faults measured in the system.
Each Dranetz power quality monitor records voltage and current at the output of a transformer in parallel with other transformers that together supply up to thirty underground network distribution feeders.
Example of a single phase fault on Con Edison network estimated to be j0.97 ohms downline from monitored substation

Example Summary Page for Faults Measured in a Network

Example Map Display of Estimated Fault Location

Tuesday, August 20, 2013

The Sign of the Sine

by Richard Bingham of Dranetz

There are certain phenomena that occur in nature which show up in so many different places that it is a bit eerie. The sine wave is one of those signs that the universe wasn't just randomly put together. If one plots the speed of the pendulum as it swings back and forth, the graph would be a sine wave. At the top of the arc, the speed is zero. Then it begins to travel faster and faster until the bottom of the arc. After reaching the bottom, it begins to slow down until it hits the other top of the arc and the speed goes to zero. The process reverses as it begins to accelerate in the opposite direction. The resulting graph is show below of the speed of the pendulum versus time.

The same curve represents the change in electrical current induced in a coil of wire as it rotates past two magnetic poles, which is the basis for an alternating current electrical generator. Not wanting to restart the debate between Edison and Westinghouse over whether AC or DC is the best way to transmit electrical energy, AC is how most electrical energy is transferred between electrical suppliers and the loads. Within loads, some devices change the voltage in to DC, such as those typically called electronic loads. Integrated circuits within personal computers, VCRs, or clock radios typically run off of either 5 or 12 Vdc (though newer circuits run on lower voltages (3.3 Vdc or smaller). But it is the AC voltage, or the sine wave, around which most of power quality phenomena is measured.

A sag or swell is determined by a variation in the amplitude of the sine wave. A sag is a reduction in the RMS value of the sine wave, typically below 90% of nominal, whereas a swell is an increase, typically above 110% of nominal. A seven cycle, two stage sag is shown below.

Harmonic distortion is a series of sine waves superimposed on each other. A transient, such as a PF cap switching generated event, can be decomposed into a series of sine waves. The oscillation following the initial negative going transient usually has a frequency between 400 and1500 Hz, compared to the fundamental power frequency of 50 or 60 Hz. As Fourier's Theorem states, any periodic waveshape can be represented by the sum of a series of sine waves. Even square wave and sawtooth waves are but a series of sine waves.

Power factor is based on sine waves. The method of measuring PF in the past was based on the difference in time or phase angle between the voltage and current. This is referred to as displacement PF. Electrical motors, which make up 60% of the load in the United States, have a current sine wave that lags behind the voltage sine wave, as a motor is mostly a coil of wire,which is an inductor. Unfortunately in today's harmonic rich electrical environments, this method no longer works. Today, true power factor is defined as watts divided by voltage amperes, or how much work is done versus the energy transferred.

Though the sine wave is really magical, most designers of equipment to be powered from the AC voltage waveform have made the assumption that the shape of the waveform will be basically sinuoidal, with the amplitude between certain limits (typically +/- 10%) and frequency stable. When events, such as large motor starts or downed wires, cause the sine wave to exceed these limits, it is usually a sign that a power quality event has occurred and possibly equipment malfunction has resulted.

Tuesday, August 13, 2013

Electrical Systems Reliability is Paramount

Power Quality has always been a key issue for healthcare facility managers. With the rapid advances in medical technology, hospitals, medical clinics and laboratories increasingly rely on sophisticated electronic devices for diagnosis, treatment and monitoring. This reliance demands a high degree of power quality and reliability to prevent disruption of mission-critical operations and procedures. Power quality disturbances can be caused by a range of internal and external phenomena and often re-occur because the location and nature of the event is not well understood or identified
While the costs of downtime or failures can result in thousands of dollars per hour, the costs of power and equipment failures in critical patient operations are immeasurable.
The Dranetz PowerGuide 4400
Dranetz Power Quality analyzers are ideal for proactively monitoring the power systems of healthcare facilities.
Never before has power quality and reliability been such a key issue for facility managers. Not only can the cost of downtime run into thousands, or even millions of dollars per hour, but power quality events can impact sensitive equipment such as servers, motors, process equipment and computers. This end-use equipment is often interconnected within networks, industrial processes and power infrastructure and can be negatively affected by events that arise both from the supplying power system and are generated within the facility. Power monitoring is key to maximizing uptime and ensuring all power infrastructure is functioning properly.

Friday, August 2, 2013

Wednesday, July 24, 2013

Applications for the PowerXplorer PX5-400

Mil Standard 1399 Testing

Mil Standard 1399 Testing
This interface standard for shipboard systems is the approved testing protocol for naval sea standards and all relevant departments within the US DOD. The electric power system serves a variety of user equipment including aircraft elevators, communication systems, weapon systems, and computers. The testing protocol is used to verify compatibility with a prescribed list of characteristics and tolerances--transients, sags and spikes, unbalance, frequency tolerances and characteristics and harmonics. Recommended testing apparatus—a voltmeter, frequency meter, oscilloscope, harmonics meter, and current transformers—can all be replaced with one instrument, the Power Xplorer PX5-400.

Power Measurement

Power Measurement
Equipment being used in these applications must be tested in all operating modes, including 400 Hz, to ensure that critical test and operational equipment fits with the power supply. The Power Xplorer PX5-400 collects a range of parameters—from load-related factors such as watts, VA, VAR, frequency instability, power factor and load excursions—to power quality information including sags, swells, transients and harmonics. Users can select the length and mode of data collection, including troubleshooting, data logging, power quality surveys, energy and load balancing.


The Power Xplorer PX5-400’s unique annunciator "report card" provides instant power quality answers in the field. A wide range of power monitoring data is collected, analyzed and tabulated in color-coded categories to quickly identify areas of concern, which are identified in red. Drill down for more detailed information by simply touching the intuitive touch screen to locate the source and pinpoint the root cause of power quality disturbances.

Fast Transient Capture

Fast Transient Capture
The Power Xplorer PX5-400 uses digitized high-speed sampling to capture and analyze microsecond-wide transients (Dranetz 658-like and BMI 8800-like). Transients, generated by fast-switching electronics, computer systems, aircraft components, and load transfer are immediately characterized as impulsive or oscillatory and detailed for further analysis. The Power Xplorer PX5-400 delivers a full profile, with events time stamped to the millisecond of the entire transient, to pinpoint the exact source and cause of the event.

Power Quality Diagnostics

Power Quality Diagnostics
The Power Xplorer PX5-400 has a built-in event characterizer that labels events to directly support troubleshooting and the gathering of survey data—for improving power quality and equipment reliability, as well as for matching the requirements and susceptibilities of that equipment to the incoming supply. Plus, the Power Xplorer PX5-400 captures detailed harmonics, interharmonics and subharmonics to effectively troubleshoot the complex problems caused by these events.

Equipment Testing

Equipment Testing
Evaluating and testing the performance of military components and computerized systems under true operating conditions—400 Hz or other—is key to ensuring a successful mission. The Power Xplorer PX5-400 incorporates advanced features such as RMS triggers, advanced transient capture, and cross triggering between channels to ensure that all equipment is working properly. Plus, real time reading observing during testing, startup and maintenance enable users to see results and tweak equipment on the fly.

Friday, July 19, 2013

Hospital's Power Outage Problem Solved

By monitoring the incoming and outgoing power from a UPS supplying critical power to the Cath Lab X-Ray System and using the cross triggering comparison feature, the Encore Series instrument (at the time, this instrumentation was referred to as 'Signature System') was able to pinpoint the power outage problem.
The Encore verified the interruption of the utility supply and that the UPS was doing its job, providing a "clean" supply of power to the load. However, twenty seconds passed before the emergency generator came on-line, causing downtime and confusion. The Encore data enabled the customer to determine that the X-ray Emergency Power Off switch was being incorrectly fed directly by emergency power, rather than feeding the UPS as was specified in the hospital’s power system design.

Friday, June 21, 2013

Harmonics Generated from the Source

The subject company manufactures meat products such as sausage, salami, and bologna. Most of their load consists of HVAC and refrigeration as they have about 6000 sq. ft. of cold room storage. They also have machinery such as grinders, slicers, and presses. The facility is served by a 120/240V through a utility-owned 500 kVA High-Leg Delta transformer that they share with another factory.

Interruptions occurred when a main 1200 amp circuit breaker was tripped frequently. The events occurred often and sometimes several times a day. Previous measurements had not shown the reason for the events as the highest measurement of current shown was 760 amps, which was not enough to cause the breaker to trip.

From the recordings, the following was noted:
  • At times the peak current exceeded the 1200A breaker rating without tripping the breaker. An interruption that was tied to such a peak current was detected only once during the measurement period. Further investigation from the wave forms captured determined that the voltages were distorted during such times. This distortion caused nuisance tripping of other breakers and caused the capacitor banks to fry.
  • A long-term measurement showed that the capacity of the breaker could be reached when a combination of tasks occurred at the same time.
  •  Since most of the load at this site is linear, no harmonics are generated from within the facility. When we looked outside the factory, the cause of the distortion was traced to a faulty power transformer.

Tuesday, June 18, 2013

David Jones of Reviews the Gossen Metrawatt METRAHIT ENERGY

David Jones of the EEVBlog visits the METRAHIT ENERGY

The METRAHIT ENERGY is a compact, single phase Power and Power Quality meter/logger that includes multimeter functions.  It is intended for measuring AC and DC voltage, as well as current in single-phase systems, with current being measured either directly or via a current transformer. 
With a resolution of 60,000 digits, the METRAHIT ENERGY has more than 35 different measuring functions including: active power, reactive power, apparent power, power factor and energy.  This powerful multimeter is extremely rugged and reliable with a housing made of impact resistant ABS. 

Click on the link below and see the METRAHIT ENERGY in action: 
Check out the METRAHIT ENERGY teardown by David Jones.


  • Digital hand-held multimeter with TRMS measurement
  • Power measurement (W, VAR, VA, PF): active, reactive and apparent power, power factor
  •  Energy measurement (Wh, VARh, VAh): active, reactive and apparent energy, mean power value with adjustable observation period, and maximum value
  • Power Quality Analysis: recording of over and under-voltage,sags/dips, swells, voltage peaks, and transients in 50 and 60Hz systems
  •  Harmonic analysis: RMS values and distortion components up to the 15th harmonic at 16.7, 50, 60, and 400Hz
  •  Special measuring functions: crest factor CF, conductivity nS, low resistance RSL, duty cycle %, cable length
  •  Resolution of 60,000 digits, triple backlit display
  • 1KHz / –3 dB low-pass filter available
  • Direct current measurement from 10nA to 10A, 16A for less than 30 seconds, current measurement with current transformer clamp and sensors, transformation ratio is taken into account on the display
  •  Large data memory for up to 300,000 measured values Instrument is completely remote controllable using PC software, without using the unit’s rotary switch

For more information about this and other safety and measurement
products, visit