Power Quality at the Plug Power Quality At the Plug

Name: Power Quality at the Plug Power Quality At the Plug
Uploaded: 2017-07-12T19:02:59+00:00
Duration: PTM26S41
Channel: Melvin Barton
Description: Power Quality at the Plug Power Quality At the Plug

Power Quality at the Plug Power Quality At the Plug
IDEAL INDUSTRIES Application Guide to Power Quality at the Plug Author: Brian Blanchette © 2007 Ideal Industries Power Quality At the Plug

Branch Circuit Testing
A portion of a wiring system in the interior of a structure that extends from a final overload protective device to a plug receptacle or a load such as a lighting fixture, motor, or heater © 2007 Ideal Industries Power Quality At the Plug

Safety Branch circuits include: Category II locations,and Category III locations. As you can see, homes with submersible pumps have Category IV locations as well Check your tester for safety rating © 2007 Ideal Industries Power Quality At the Plug

Circuit Integrity Three Possible Ways to Test Branch Circuits Branch Circuit Integrity The physical structure of the branch circuit Quality of the voltage supplied How connected equipment will perform Profile the Loads on the Branch Circuit Measure the energy and the load on the circuit We will examine the first and second of these in the time we have today. © 2007 Ideal Industries Power Quality At the Plug

Circuit Integrity Test the physical structure of the branch circuit Connections to receptacles and devices Connections to panel Capacity of Hot and Neutral Age, type, length and size of conductor Quality of connections, splices, pigtails, bonds Integrity of Ground Conductor HOW?? © 2007 Ideal Industries Power Quality At the Plug

Evaluating Branch Circuit Structure Step 1: Test for correct wiring polarity Step 2: Make voltage measurements Step 3: Test for neutral / ground integrity Step 4: Test Voltage Drop Step 5: Measure circuit impedance © 2007 Ideal Industries Power Quality At the Plug

Step 1: Wiring Polarity Test Common receptacle tester Detects, as go-no-go test, Hot, Neutral and Ground There can be < 100,000 ohms on the ground and a standard receptacle tester with show the circuit to be OK © 2007 Ideal Industries Power Quality At the Plug

Description Normal Range Comments Line to Neutral RMS Volt To 132 volts Different standards apply Neutral to ground RMS Voltage Less than 0.5 volts Some N-G voltage is normal © 2007 Ideal Industries Power Quality At the Plug

Step 3: Test for Bootleg or Neutral to ground Shorts SureTest indicates possible neutral to ground contact faults to within 15’ of the fault and 15’ from the panel. Looks for similar low resistance on ground and neutral conductor. © 2007 Ideal Industries Power Quality At the Plug

Test for Bootleg or Neutral to ground Shorts General Purpose testers can’t identify a “False” or “bootleg” ground Defined as an accidental short or improper bonding of ground to neutral conductors Shows up as normally wired condition with general receptacle testers Sensed by the new AFCI breakers, will trip an AFCI False ground conditions are shorts between ground and neutral. This condition will not show up on a standard receptacle tester. Only the SureTest can identify a false ground condition. If this condition exists, the SureTest will immediately display a FG on the LED display so it can be checked out prior to testing the circuit. © 2007 Ideal Industries Power Quality At the Plug

Using Voltage Drop NEC code Articles {210-19(a) FPN No. 4} {215-2(d) FPN No. 2} - “Branch circuit conductors should be sized so as not to exceed a maximum voltage drop of 3% at the farthest outlet , and that the combined voltage drop for both a branch and feeder should not exceed 5%” Measure the voltage drop at the furthest receptacle from the panel Low voltage drop indicates a low impedance system Lowers the risk of hidden hazards Improves power efficiency and operation By measuring the voltage drop at the furthest receptacle from the panel you can check the integrity of the circuit. A low voltage drop indicates a low impedance electrical system which lowers the risk of hidden hazards and improves power efficiency and equipment operation. The NEC contains several fine print notes which if taking into consideration can help minimize resistances and lower risk of hidden hazards. It will also improve power efficiency and operation. NEC code Articles {210-19(a) FPN No. 4} {215-2(d) FPN No. 2}, state in that – Branch circuits conductors be sized so as not to exceed a maximum voltage drop of 3% at the farthest outlet , and that the combined voltage drop for both a branch and feeder should not exceed 5%. [fn 1] 1. Branch Circuits – This FPN recommends that branch circuit conductors be sized to prevent a maximum voltage drop of 3%. The maximum total voltage drop for a combination of both branch circuit and feeder should not exceed 5%. [210-19(a) FPN No. 4], (1) [fn 1] 2. Feeders – Feeder conductors be sized so as not to exceed a maximum This FPN recommends that feeder conductors be sized to prevent a maximum voltage drop of 3%. The maximum total voltage drop for a combination of both branch circuit and feeder should not exceed 5%. [215-2(d) FPN No. 2], (1) National Electrical Code and NEC are resisted trademarks of the National Fire Protection Agency (1) Source © 2007 Ideal Industries Power Quality At the Plug

Testing under a load and calculating voltage drop can identify common wiring problems Undersized wiring for load or length of run NEC (a) FPN no.4 states that conductors be sized to provide reasonable efficiency of equipment operation High resistance connections Loose or corroded connections Poor splices Defective devices Voltage drop can detect an estimated 90% of defects on a branch circuit To identify these problems, the circuit must be tested using a known load. Testing under load and measuring the voltage drop will identify wiring problems, such as undersized wire or high resistance connections, caused by loose or corroded connection, poor splices or bad devices. In fact almost 90% of hidden defects on a branch circuit can be identified by measuring the integrity of a branch circuit with the voltage drop test. © 2007 Ideal Industries Power Quality At the Plug

Practical Application for Voltage Drop testing The Philadelphia Housing Development Corporation) Contractors must perform the 15-ampere-load test prior to insulating older row homes with blown insulation in attic and crawl spaces. Smoldering fires had been associated with half a dozen installations. The PHDC found that 70% of the homes flunked the 5% maximum voltage drop test with “a cluster around 6%”. The PHDC arbitrarily established 10% as an unacceptable voltage drop, beyond which the contractor must repair/replace the circuit prior to proceeding with the insulation project. (HUD recently adopted a similar requirement, according to reliable sources) © 2007 Ideal Industries Power Quality At the Plug

General tester can not identify high resistance or series faults Nor can they identify a neutral to ground bond Glowing contacts in copper or aluminum wiring High resistance in Back-wired devices like receptacle Loose or corroded connections Bad splices Hot plugs, or high resistance contact between outlet to plug. A high resistance connection can result in hot spots or glowing connections which can breakdown insulation and create poor efficiency of the electrical system Circuit testers are excellent for quick checks and general function branch testing, but are not suited as an analysis tool. The object in any electrical distribution system is to minimize impedance (resistance) to energy. High resistance results in higher energy usage or heat. A simple Static non-load test preformed with a circuit tester or digital voltage meter cannot identify hidden defects in the circuit which can cause high resistance. Problems and hazards arise when current flows through these high impedance defects which results in hot spots, leading to fires, breakdown in insulation, and poor efficiency of the electrical system, which can contribute to erratic equipment operation. © 2007 Ideal Industries Power Quality At the Plug

ASSC or Available Short Circuit Current Hot to Neutral ‘Ampacity’ Hot/neutral/ground ‘Ampacity’ A look at the energy available ASSC, along with resistance of the conductors, and voltage drop, gives us a snapshot of the entire circuit. Ohm’s Law Method – Single-Phase Only Voltage drop of the circuit conductors can be determined by multiplying the current of the circuit by the total resistance of the circuit conductors: VD = I x R. “I” is equal to the load in amperes and ”R” is equal to the resistance of the conductor as listed in Chapter 9, Table 8 for direct current circuit, or in Chapter 9, Table 9 for alternating current circuits. The Ohm’s law method cannot be used for three-phase circuits. © 2007 Ideal Industries Power Quality At the Plug

Voltage Performance Monitor
What is a Voltage Performance Monitor? Why do I need to measure the integrity of the Voltage? What are the factors and features I need? © 2007 Ideal Industries Power Quality At the Plug

Step 2: Voltage Performance Two Steps to test the Voltage Performance of the branch circuit: Perform Harmonic Analysis of Branch Capture and Analyzer Voltage Events © 2007 Ideal Industries Power Quality At the Plug

What is Voltage performance? Voltage performance? Amplitude Must be measured over time. Must meets some excepted standard What would be a relevant Standards ? How do we compare voltage over time to these Standards? © 2007 Ideal Industries Power Quality At the Plug

What Can we do with the information Eliminate sources of equipment failure Determine cause of voltage event using time stamps Determine if protective devices are effective Identify isolated or widespread problems Reduce Warranty Cost and Expense © 2007 Ideal Industries Power Quality At the Plug

How do we compare voltage over time to these Standards Each voltage waveform must be measured and compared to the standard: If outside the range, timer starts, measures in cycles per second to the end of the event are taking. When an important event is detected, The voltage of the event is logged The duration of the event is logged The day/date/time to the second of the event is logged © 2007 Ideal Industries Power Quality At the Plug

Key Points for comparison Only important events are logged Events are sorted by Time (log) Events are sorted by Type (event) Waveform shape is measured for THD © 2007 Ideal Industries Power Quality At the Plug

Voltage Performance Testing
What are these problems called? Sag – low voltage for brief periods (dips) Swell- high voltage for brief periods (surges) Voltage Transient- impulses (spikes) THD for Total Harmonic Distortion (noise) © 2007 Ideal Industries Power Quality At the Plug

What Utilities Promise: ANSI C84 ANSI C84 Range A Fully Satisfactory Performance on 120Vac 114V to 126V continuous 95% to 105% of nominal Range B Acceptable Performance on 120Vac circuit 106V to 127V continuous 87% to 106% of nominal How does a standard say one thing, yet mean another? Here is the actual wording from one real “Definition of Service” regarding the application of ANSI C84: © 2007 Ideal Industries Power Quality At the Plug

What Utilities Deliver! Service Agreement b.Exceptions to Voltage Limits (Ed.Note – ANSI C84) Voltage may be outside the limits specified when the variations: 1) Arise from the temporary action of the elements. 2) Are infrequent momentary fluctuations of a short duration. 3) Arise from service interruptions. 4) Arise from temporary separation of parts of the system from the main system. 5) Are from causes beyond the control of (power utility). c. It must be recognized that, because of conditions beyond the control of (power utility) or customer, or both, there will be infrequent and limited periods when sustained voltages outside of the service voltage ranges will occur. Utilization equipment may not operate satisfactorily under these conditions, and protective devices may operate to protect the equipment © 2007 Ideal Industries Power Quality At the Plug

Power Quality problems are very expensive, but…. UNTIL NOW Power quality required very expensive analyzers Computers to set them up, Software to analyze Experts to review the data Power Quality Monitors were too expensive for branch circuits © 2007 Ideal Industries Power Quality At the Plug

Total Harmonic Distortion Measure at service entrance & points of connections IEEE 519 limits for voltage THD < 5% for most facilities <3% for Hospitals and Airports © 2007 Ideal Industries Power Quality At the Plug

Transient Voltages Measure and record the time and voltage Transients cause failure of communication control and datacom devices Transients destroy insulation and capacitors Determine if transient protection is working (TVSS, SSDs) © 2007 Ideal Industries Power Quality At the Plug

Power Quality At the Plug
Branch Circuit Power Quality Branch Circuit Test Pass/fail Comments Line Voltage 108 – 132 Low or high voltage will harm equipment. % Voltage 15 Amp. Load <5.0% NEC Part , FPN 4. Excessive voltage drop can cause fires. (test for 15 amp. Circuit) % Voltage 20 Amp. Load NEC Part , FPN 4. Excessive voltage drop can cause fires. (test for 20 amp. Circuit) Voltage between neutral and ground < .5 Volts Higher voltages upset microprocessor operation. Can often be noise. Phase Conductor Impedance <.25 Ohms IEEE recommends less than .25 Ohms from any outlet to the building entry. Neutral Conductor Ground Conductor Impedance IEEE recommends less than .25 Ohms. Critical for proper operation of surge protection devices. © 2007 Ideal Industries Power Quality At the Plug

THANK YOU FOR YOUR TIME AND ATTENTION Power Quality at the Plug
Application Guide to Power Quality at the Plug QUESTIONS PLEASE! © 2007 Ideal Industries Power Quality At the Plug

Power Quality at the Plug Power Quality At the Plug

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