Critical Power Perspectives Every power system problem is critical. - - PowerPoint PPT Presentation

Critical Power

Perspectives

• Every power system problem is critical.
• Electricity is required for jobs, income, food, and shelter.
• Many teachings regarding controlling power quality are wrong.

Voltage and Current Perspectives: Cause and Effect

• Current is dependent on voltage.
• Without voltage, there is no current.

Harmonics

• Non-linear loads fed by switch-mode power supplies cause harmonics.
• Harmonics are distortions in pulses or bursts of current.
• The distorted current results in a distorted voltage waveform on the power system.

The Traditional “Solution”: Treating the Effect

• Each load draws only the current it requires. However, all loads share the same voltage.
• Applying additional current to correct the problem is not an adequate solution.
• The “current” approach only provides limited improvement with inevitable failure.

Voltage Instability in Equipment

• Machine controls, variable-speed drives, and CNC equipment are sensitive to voltage

instability and voltage imbalance.

• Machinery operates on line voltage. Noise and instability are measured in phase voltage.
• Another “attempt to solve the symptom” is to install an “Amp-Trap” filter, which drains the

harmonic current to ground or line-to-line.

• A 200 HP variable-speed drive has a 350 kVA power filter to remove the 5th harmonic

(5x60 = 300 Hz). 350 kVA at 480 volts results in a current draw over 400 amps.

Phase Voltage Notching (Voltage Distortion) Causing Waveform Distortion with Voltage Correction OFF Phase Voltage Waveform Distortion Reduced with Voltage Correction ON

Voltage Distortion: Without and and With Correction

Third Harmonic 38% with Voltage Correction OFF Third Harmonic Reduced 98% with Voltage Correction ON

Voltage Harmonics: Without and and With Correction

Arc Fla lash: Employee and Equipment Safety

• Most grounds in a power system start as arcing ground faults.
• An arc ionizes the air, creating a conductive path, which can result in an arc flash hazard.
• Two phases arcing to ground cause a phase-to-phase fault through ground.

Preventing an Arc Flash event (See Arc Flash Mitigation file for additional details)

• Presently, one to two people die per day due to arc flash, and 80 more are injured.
• Stabilizing the voltage potential between phase and ground prevents arc flash at the

beginning of the event.

• When the phase voltage potential is kept at a nominal level, multiple ground faults do not

cause arc flash.

Another “Solution” for the Symptom

• Many manufacturers recommend adding current smoothing reactors.
• Installation requires the equipment to be shut down, the power wiring to be

disconnected, followed by mounting the reactor inside the drive enclosure (if there is panel space), and wiring the reactor in series to the drive.

• Although this “solution” does smooth current, it also causes a voltage loss or drop based
• n the current and reactance, thus limiting the voltage.
• As a result, the motor’s acceleration time increases, and its torque is reduced.
• This symptomatic solution has no voltage control, no restoration of the phasor phase

angle, and worst of all: no voltage protection and minimal noise filtering.

Observ rving the Root Cause of f Shortened Life Expectancy in LED Lighting

Contrary to common belief, it is voltage that damages LED lights, not current. Every component shown in this circuit diagram is vulnerable to damage from voltage spikes. MOVs (Metal Oxide Varistors) are a common symptomatic treatment applied to LED lighting. TVS (Transient Voltage Suppressing) diodes attempt to limit the voltage across the LED array.

Yet Another Attempted Symptomatic “Solution”

• TVSS (Transient Voltage Surge Suppressor) manufacturers recommend adding their

products to address voltage problems.

• Installation requires short wiring and mounting (if there is panel space).
• This “solution” causes a voltage limit based on the amount of degradation present in the

MOV, as well as the available current, which limits the voltage.

• Unfortunately, MOVs degrade with every spike and cause a very high current spike.
• A TVSS has no voltage balancing control, no restoration of the phasor phase angle, and

worst of all: no noise filtering effect.

• A TVSS is a “one-hit wonder”. It may survive one “hit”; however, many do not provide

notification upon failure. At this point, they offer no protection.

• A TVSS does not protect an ungrounded WYE or DELTA (three-phase, three-wire) power

system.

Comparison of f TVSS to VSGR

Minimal voltage protection Wide range of unprotected voltage Voltage envelope with VSGR ON

MOV-based TVSS

Correcting the Voltage Waveform: A Solution to the Root Cause

Benefits of Correcting the Voltage Waveform

• Requires less power to clean the system: draws approximately 1 amp. (0.25% of the

current used by the traditional solution)

• Provides equal phase voltages.
• Prevents voltage spikes from starting.
• Protects the system from arcing ground faults.
• Reestablishes the 120° phase differential.
• Prevents arc flash hazards.
• Ensures clean power during a shutdown.

Voltage Waveform Correction: The Root Cause Solution

• Compatible with a variety of power system designs and voltage classes.
• Voltage waveform correction is applicable to power systems from 5 volts DC to high

voltage AC, including 600V class, 5 and 15kV medium voltage and high voltage classes.

• This solution is also available for office and residential use.
• Voltage waveform correction uses only a small percentage of the floor space required of

solutions that control current.

• Because voltage waveform correction equipment is installed in parallel, there is no

production downtime as there is with line reactor installation.

• Power problems do not need to be an unsolvable “fact of life”. They can be eliminated.

Correcting the Voltage Waveform: A A Cause Solution

Arcing ground faults on C phase Phase voltages balanced and stabilized with VSGR ON Transient voltage spikes exceeding 560 volts

IE IEEE Requirements

• In marine vessel applications, the vessel is required to have insulation monitors, ground

detection, and resistance grounding techniques.

• Voltage waveform correction systems provide all of the above mentioned functions,

including local ground detection, remote ground indication and alarm, as well as eliminating the presence of an arcing ground faults and arc flash hazard.

• The IEEE has determined that a VSGR (Voltage Stabilizing Ground Reference) is covered

under the 142 Grounding Standard.

Applications

• In order to protect all three-phase power systems, one VSGR is required for each power

transformer.

• This solution provides transient voltage spike protection, arcing ground fault protection,

phase voltage balancing, and arc flash mitigation.

• In three-phase, three-wire power systems, a voltage-stabilizing ground reference also

eliminates differential phase distortion (120 degree phase differential).

• In grounded WYE (3-phase, 4 or 5 wire) power systems, excessive harmonics at the point
• f common coupling may also require a harmonic silencer to reduce harmonics to a

satisfactory level.

• Power systems get their voltage and frequency reference from the grid. Adding a VSGR to

a power system provides a controlled shutdown during storms and power switching.

• This can also be applied to a VFD (Variable Frequency Drive) output to stabilize and clean

up the power to a motor by removing voltage spikes and reducing phase voltage

• harmonics. This application is called a Drive Voltage Stabilizer.

Phase Voltage Im Imbalances

Phase voltage 61% imbalance with VSGR OFF Phase voltages balanced with VSGR ON

Dif ifferential Phase Dis istortion (O (Off Event)

Voltage imbalance with VSGR OFF Phase voltage imbalance Phase differential distortion Impedance differential proportional with voltage

Dif ifferential Phase Dis istortion (O (On Event)

Current 180 degree Phase shifted causing CEMF to low phase voltage (Phase A) The indication of negative resistance is simply the power being directed back into the low voltage phase, reverse flow or counter electromotive force. Voltage balanced with VSGR ON Phase voltage 120 degree differential restored with VSGR ON Current proportional with phase voltage

Power Phasors Phases B and C (O (On Event)

Notice the power used by phase C Notice the power used by phase B

Power Phasors Phase A (O (On Event)

Notice the power directed back into phase A (negative wattage)

Phase Voltage Harmonics

Phase voltage harmonics with VSGR OFF Phase voltage harmonics filtered with VSGR ON

Questions

We are now available for a few general questions. Specific questions will be handled after the presentation and during the upcoming break. Thank you, William Hinton

Applied Energy LLC. Director of Engineering

(989) 327-8389 bill@applied-energy.us www.Phaseback.com