Voltage Regulators

Outline

• Regulator Function & Purpose• What is inside• Neutral Position • Nameplate• Bypassing• Basic Control Settings

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This work by Alpena Community College’s Sustainable Solutions for Northeast Michigan, a Department of Labor, TAACCCT funded project, is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

Voltage Regulator Function

What is the function of a voltage regulator?

The basic function of a voltage regulator is to monitor voltage and maintain it within a preset range.

TRANS-FORMER

End of line

Vo

ltag

e

Distance

VLD = Voltage drop due to line losses

VLD

CU

RR

EN

T

TIME OF DAY

12am 6am 12pm 6pm

LOAD CURRENT VS TIME OF DAY

How to Reduce Voltage Drop

Change taps on distribution transformers Change taps of substation transformer Reconfigure system Install larger conductor Increase system voltage Install line capacitors INSTALL LINE REGULATORS

Voltage Regulators Purposes

Primary Purpose Provide regulated voltage to meet power

quality criteria Secondary Purposes

Increase revenue Peak shaving Conservation voltage reduction Metering point

Power Quality

What is the right voltage level? ±10% (132 to 108) Outage ±5% (126 to 114) Guideline ±2.5% (123 to 117) Customer

expectation

ANSI TYPE B

ShuntWinding

SeriesWinding

Vp = 1000V

Conventional two-windingtransformer

Vs = 100V

++

- -

10:1

Vp = 1000V

Step-Up Autotransformer

Vs = 1100V

++

- -

Vp = 1000V

Step-Down Autotransformer

Vs = 900V

++

- -

12

34

56

78

N+

-

+

-

Step Regulator

12

34

56

78

N+

-

+

-

Step Regulator withRevsersing Switch

Non-Bridging

N 1 2 3 4 5 6 7 8

1.25%

Bridging

N 1 2 3 4 5 6 7 8

1.25%

N 1 2 3 4 5 6 7 8

1.25%

SL

S

SHUNTWINDING

CONTROL

SERIES WINDING

CONTROLWINDING

TYPE BREGULATOR

REVERSINGSWITCH

CURRENTX-FORMER

L

Voltage Regulator Connection in a Single-Phase Circuit

SourceA

N

Bypass Switch

ShuntLightningArrester

Disconnects

SeriesLightningArrester

SL

S

L

Regulator Neutral

720V

Regulator Raise Operation

Regulator Raise Operation

And So It Goes

Picking up More Series Winding

Full Raise

To Lower Voltage

Regulator Lower Operation

7110V

Switching Checklist Putting Regulator In Service

• Check potential transformer settings.

Back Panel with Modular Terminals & Switches

Optional FO-RS232 Board

TB2

TB1

RCT2 RCT1V6, V1, & C switches

Regulator Hazards

BYPASSING

ABSOLUTELY, POSITIVELY

• A voltage regulator MUST be in the neutral position in order to “bypass” it while it is energized.

• A line/service technician must know how to operate the controls in order to maneuver the regulator into the neutral position.

AEP Safety Manual E 9.01 States:

“Voltage regulators shall be placed in the neutral position,

verified by two approved methods to be in the neutral and the control circuit made inoperative before they are

bypassed.

Voltage Regulator Neutral PositionMechanical Indication: Position indicator

Voltage Regulator Neutral Position

Electrical Indication: Neutral light

Hastings Neutral Detector

• Is a specifically designed voltmeter installed on a hot stick that measures the difference in voltage between the source and load conductors.

Low impedance bypass loop

Regulator Bypass SwitchesNon-sequenced SwitchNon-sequenced Switch

Regulator Bypass SwitchesKearney (sequenced switch)Kearney (sequenced switch)

Switching ChecklistTaking Regulator Out Of Service

• Check position of regulator.

• Place regulator in the neutral position.

• Turn control to “off”.

• Verify neutral position.

• Disable control panel power source.

• Test regulator to be in neutral.

• Operate bypass switch as required depending on type of switch.

Bypassing - Remove ProcedureRegulator Connected Line-to-Ground (GY)

Source Load

Phase A

Neutral

SL

LS

S-DIS L-DIS

B

Start 1 2 3

B O C C C

S-Dis C C C O

L-Dis C C O O

Step 1 is Critical Operation.

Bypassing - Install ProcedureRegulator Connected Line-to-Ground (GY)

Source Load

Phase A

Neutral

SL

LS

S-DIS L-DIS

B

Start 1 2 3

B C C C O

S-Dis O C C C

L-Dis O O C C

Step 2 is Critical Operation.

Switching Checklist Putting Regulator In Service

• Check potential transformer settings.

• Check regulator in neutral and off position.

• Check power source disabled.

• Test regulator to be in neutral.

• Operate bypass switch as required.

• Enable control panel power circuit.

• Place regulator control to “automatic”.

De-energizing

When should a regulator be de-energized before When should a regulator be de-energized before bypassing?bypassing?

The regulator is inoperative and cannot be returned to the neutral position.

The regulator cannot be insured to be in the neutral position.

BASIC CONTROL SETTINGS

• Set Voltage• Bandwidth• Time Delay• Control operating

mode• Reverse sensing

mode

• Configuration• System voltage

(nominal)• P.T. & C.T. ratios• Line drop

compensation

Set Voltage

• The voltage level (in 120V base) to which the control will regulate

• Settable for both forward & reverse power flow

• Forward set voltage = Function code (FC) 1

• Reverse set voltage = FC 51

• Default values are 120.0V

Bandwidth

• The total voltage range around the set voltage which the control will consider acceptable

• Acceptable voltage range defined as: Range = SV +/- 1/2 BW

Time Delay

• The number of seconds the control waits, from the start of an out-of-band condition, before initiating a tap change

• Typical values are 30 through 90 sec….

Time Delay & Cascading Regulators

3-phaseLTC

transformerTD = 30 SEC

SVRTD = 45 SEC

SVRTD = 45 SEC

SVRTD = 45 SEC

SVRTD = 75 SEC

SVRTD = 60 SEC

SVRTD = 75 SEC

Rule 1: Each succeeding regulator in series down line from the source requires a longer time delayRule 2: The minimum time delay from one regulator to the next in cascade is 15 seconds

Control Operating Mode

• Defines for the control how to respond to out-of-band conditions

• Options– Sequential (FC 42 = 0)– Time integrating (FC 42 = 1)– Voltage averaging (FC 42 = 2)

120.0120.0

121.0121.0

119.0119.0

c=0 c=10

time

SEQUENTIAL

10 sec. out-of-band 5 sec .

in-bandcounterresets tozero

c=0 c=30 2 sec delays(horizontal)

tap changes(vertical)

30 sec. out-of-band

in-band

Given: SV=120.0BW=2.0TD=30

SVSV

UBEUBE

LBELBE

SVSV

UBEUBE

LBELBE

c=0 c=10

time

TIME INTEGRATING

10 sec. out-of-band 5 sec. in-band;

counter decremented1.1/sec in-band

c=4.5 c=302 sec delays(horizontal)

tap changes(vertical)

25.5 sec.out-of-band

in-band

Given: SV=120.0BW=2.0TD=30

121.0121.0

120.0120.0

119.0119.0

SVSV

UBEUBE

LBELBE

c=0

time

VOLTAGE AVERAGING

10 sec. out-of-band 5 sec.

in-band

c=30

tap changesw/no 2 sec.delay betweentaps

in-band

Given: SV=120.0BW=2.0TD=30

averagevoltage

121.0121.0

120.0120.0

119.0119.0

out-of band

Reverse Sensing Mode

• Reverse sensing mode defines for control what RPF (Reverse Power Flow) is and how it is to react

• Options are locked forward, locked reverse, reverse idle, bi-directional, neutral idle, and co-generation

Configuration

• Defines for the control how the regulator is connected in the power system

• Necessary for proper phase relationships

• Configuration = FC 41

• Options– Wye (FC 41 = 0)– Delta lag (FC 41 = 1)– Delta lead (FC 41 = 2)

System Line Voltage

• The nominal system voltage at which the regulator is to operate

• System line voltage = FC 43

• Obtain value from regulator nameplate

Overall P.T. Ratio

• Ratio of system line voltage to voltage sensed by the control when in neutral position

• Overall PT ratio = FC 44

• Obtain value from nameplate based on selected system line voltage

Nameplate System Voltages14400 Volts, 60 Hz

TAP CONTROL INTERNAL R.C.T. TEST OVERALLIN LOAD WDG.TAP P.T. TAP TERMINAL POT.

USE VOLTS (TANK) RATIO (CONTROL) VOLTAGE RATIO

14400 E1 120:1 120 120 120:113800 E1 120:1 115 120 115:113200 E1 120:1 110 120 110:112000 E1 120:1 104 115 104:17970 E2 60:1 133 120 66.5:17620 E2 60:1 127 120 63.5:17200 E2 60:1 120 120 60:16900 E2 60:1 115 120 57.5:1

Note: The ratios may be different for each load current rating

Line Drop Compensation

VIN VOUT

I

VDROP

VCOMP

VCOMP = VOUT - VDROP

S L

SL LoadCenter

FC 6

FC 9

FC 8FC 7

R VR FC 4 X VX FC 5

R X