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Electric Power Voltage Sag Solutions-The PQSI Coil-Lock

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Electric Power Voltage Sag Solutions: Coil-Hold-in-Devices (Coil-Locks)Presented by: Power Quality Solutions, Inc. (PQSI) Knoxville, Tennessee USA

February 2009

Symptoms of Electric Power Quality ProblemsPower Quality problems are failure or misoperation of customer end-use equipment caused by voltage, current or frequency deviations

The Voltage Sag Solution: PQSI Coil-Locks

A cost-effective, low intrusive way to protect your vital equipment from voltage sags and dips.

Energy User Surveys*Typical Number of Facility Voltage Incidents/Year

Voltage Deviation < 0.02 Seconds Your Text

Up to 3 Seconds

110-120% 106 110%

> 700 > 700

06 0 200

87 106%70 87% 25 87%

Normal> 240 > 240

Normal20 140 0 - 16

Most devices will operate here

Devices protected by a Coil-Locks will operate here

*Electric Power Research Institute (EPRI), Canadian Electric Associations (CEA), and National Power Laboratory (NPL)

Typical Number Facility Voltage Sag Events*

The PQSI Coil-Lock is not time based, therefore it maintains operation during

sag events.

*Electric Power Research Institute (EPRI), Canadian Electric Associations (CEA), and National Power Laboratory (NPL)

Typical Voltage Sags in RMS TermsPower Quality Your Text

Example of a Voltage Sag RMS Variation

Variation Category Voltage Sags (RMS Disturbance)


Method Your Textof

Your Text Magnitude & Duration

Typical Your Text Causes Your Text Utility System Faults Motors Starting Load Variations Weather Conditions

Typical Voltage Sag Events* in Real-Time Terms

Duration (4 Cycles) 1 0.5

0 0 -0.5 -1









Magnitude (50% of Nominal)

* Voltage sag 50% depth with duration that can vary from 8 milliseconds to > 3 seconds due to across the line motors starting in industrial processes, air conditioners, and utility activities.

Process Solenoid Relay & Contactor Operated Devices that can trip with 25% Voltage Sag Events

PQSI Coil-Lock Coil-hold-in-Device Protects for 75% Deep Sags (i.e. 25% Remaining Voltage)

PQSI Coil-Lock Coil-hold-in-Device Provides SEMI F47 Voltage Sag ImmunityDuration of Voltage Sag in Seconds Percent of Equipment Nominal Voltage0.01 0.02 100 90 80 70 60 50 40See Note 1 for Explanation of this Pass/fail point

0.1Equipment required to Operate in this region





3020 10 0Equipment not required to Operate in this regionArea included in Specification 0.05 to 1 Second

Legend Pass Fail, but not required to pass Fail


Voltage Sag Immunity SEMI F47SEMI Stepper/Washer, 240V 50 Hz powerModel 2200, SN 99SW4502, 5/00 Note 1: This point (50% sag for 12 cycles) initially failed for L3-L1 sags with a High Velocity Pressure Sprayer fault, but passed for L1-L2 and L2-L3 sags.

PQSI Coil-Lock Applications1Coil-Locks Eliminate Weak Links Relays, contactors, and motor starters are used extensively in commercial and industrial facilities to control business machines and process equipment. These devices often have a low tolerance to electric service voltage sags, and are frequently diagnosed as weak links in automated production lines.


Coil-Locks Eliminate Costly Equipment Shutdown During common voltage sags, the solenoid coils in these motor-driven systems may de-energize long enough to cause the power circuit mechanical contacts to open (chatter), and the connected electrical equipment to shutdown. The Coil-Lock eliminates costly process shutdown, installs in minutes, and can be a cost-effective alternative to other voltage sag protection methods.


Coil-Locks Eliminate Disruption of Operations This situation can impact an entire manufacturing facility The Coil-Lock is available in different models to be compatible with most solenoid operated relays and contactors, and is ideal for protecting master control relays, and E-stop circuits. .

Good Place to Begin Hardening: Emergency Off (EMO) Circuit (Simplified)

PQSI Coil-Lock: Simple Installation

PQSI Coil-Lock: Field InstallationsCoil-Lock

Coil-Lock NEMA Size 1 NEMA Size 3


Coil-LockNEMA Size 5

SEMI F47 Equipment

PQSI Coil-Lock: 120Vac & 240Vac ModelsCoil-Lock 120Vac Models

Coil-Lock 240Vac Models

PQSI Coil-Lock: Selective Power ConditioningCost BreakdownsSag Protection Options PQSI Coil-Lock Voltage Dip Proofing Inverter Constant Voltage Transformer (CVT) Initial Cost Installation Cost Maintenance Life Cycle Cost Cost

$ $$$$$

$ $$$$

None RequiredStorage/Mech Devices None Required

FixedVariable Fixed

Dynamic Sag Corrector (DYSC) Uninterruptible Power Supply (UPS)Know-Trip

$$$$ $$$$ $$

$$ $$ $

Storage/Mech Devices Storage/Mech DevicesNone Required


Variable Variable

SummaryPower line variation impacts such as Voltage sags can be minimized Knowledge of the electrical with PQSI Coil-Locks. environment can help inapplying PQSI Coil-Locks to present process equipment and the design of new equipment.

Power line variation impacts such as voltage sags can be minimized with PQSI Coil-Locks. Strategy

Challenges Forward

HistoryCollaboration between end-users, utilities, and manufacturers can be cost-effective in solving these power quality issues.

Thank You!Special Thanks to: EPRI, CEA, and NPL Corporations for use of their ongoing Power Quality System Compatibility ResearchPrepared by Power Quality Solutions, Inc. Knoxville, TN USA

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