Voltage Regulators Outline Regulator Function Purpose What is

Voltage Regulators

Outline • • • Regulator Function & Purpose What is inside Neutral Position Nameplate Bypassing Basic Control Settings “This workforce solution was funded by a grant awarded by the U. S. Department of Labor’s Employment and Training Administration. The solution was created by the grantee and does not necessarily reflect the official position of the U. S. Department of Labor. The Department of Labor makes no guarantees, warranties, or assurances of any kind, express or implied, with respect to such information, including any information on linked sites and including, but not limited to, accuracy of the information or its completeness, timeliness, usefulness, adequacy, continued availability, or ownership. ” 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.

TRANSFORMER VLD = Voltage drop due to line losses Voltage End of line VLD Distance

CURRENT LOAD CURRENT VS TIME OF DAY 12 am 6 am 12 pm TIME OF DAY 6 pm

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

Series Winding Shunt Winding ANSI TYPE B

Conventional two-winding transformer + + Vs = 100 V Vp = 1000 V - - 10: 1

Step-Up Autotransformer + + Vp = 1000 V Vs = 1100 V - -

Step-Down Autotransformer + + Vp = 1000 V - - Vs = 900 V

+ - 8 7 6 5 4 3 2 1 + N Step Regulator

+ - 8 7 6 5 4 3 2 1 + N Step Regulator with Revsersing Switch

1. 25% N 1 2 3 4 5 6 7 Non-Bridging 8

1. 25% N 1 2 3 4 5 6 Bridging 7 8

REVERSING SWITCH 1. 25% SERIES WINDING L S N 1 2 3 4 5 6 7 8 CURRENT X-FORMER TYPE B REGULATOR CONTROL SHUNT WINDING CONTROL WINDING SL

Voltage Regulator Connection in a Single-Phase Circuit

Regulator Neutral 720 V

Regulator Raise Operation

Regulator Raise Operation

And So It Goes

Picking up More Series Winding

Full Raise

To Lower Voltage

Regulator Lower Operation 7110 V

Switching Checklist Putting Regulator In Service • Check potential transformer settings.

Back Panel with Modular Terminals & Switches V 6, V 1, & C switches RCT 2 RCT 1 TB 2 TB 1 Optional FO-RS 232 Board

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 Position Mechanical 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 Switches Non-sequenced Switch

Regulator Bypass Switches Kearney (sequenced switch)

Switching Checklist Taking 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 Procedure Regulator Connected Line-to-Ground (GY) Source Load Phase A B L-DIS S-DIS L S Start 1 2 3 B O C C C S-Dis C C C O L-Dis C C O O SL Neutral Step 1 is Critical Operation.

Bypassing - Install Procedure Regulator Connected Line-to-Ground (GY) Source Load Phase A B L-DIS S-DIS L S SL Neutral Start 1 2 3 B C C C O SDis 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 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 120 V 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. 0 V

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 SVR TD = 45 SEC TD = 75 SEC SVR SVR TD = 45 SEC TD = 60 SEC TD = 75 SEC 3 -phase LTC transformer SVR TD = 30 SEC TD = 45 SEC Rule 1: Each succeeding regulator in series down line from the source requires a longer time delay Rule 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 Time integrating Voltage averaging (FC 42 = 0) (FC 42 = 1) (FC 42 = 2)

SEQUENTIAL c=30 c=10 c=0 30 sec. outof-band 121. 0 120. 0 2 sec delays (horizontal) UBE in-band time 119. 0 SV LBE 10 sec. outof-band counter resets to zero 5 sec. in-band tap changes (vertical) Given: SV=120. 0 BW=2. 0 TD=30

TIME INTEGRATING c=30 c=10 c=4. 5 121. 0 25. 5 sec. out-of-band 120. 0 2 sec delays (horizontal) UBE in-band time SV LBE 119. 0 10 sec. out 5 sec. in-band; of-band counter decremented 1. 1/sec in-band tap changes (vertical) Given: SV=120. 0 BW=2. 0 TD=30

VOLTAGE AVERAGING c=0 average voltage out-of band 121. 0 c=30 tap changes w/no 2 sec. delay between taps in-band 120. 0 time UBE SV LBE 119. 0 10 sec. outof-band 5 sec. in-band Given: SV=120. 0 BW=2. 0 TD=30

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 Delta lag Delta lead (FC 41 = 0) (FC 41 = 1) (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 Voltages 14400 Volts, 60 Hz TAP IN USE LOAD VOLTS CONTROL WDG. TAP (TANK) 14400 13800 13200 12000 7970 7620 7200 6900 E 1 E 1 E 2 E 2 INTERNAL R. C. T. TEST OVERALL P. T. TAP TERMINAL POT. RATIO (CONTROL) VOLTAGE RATIO 120: 1 60: 1 120 115 110 104 133 127 120 115 120 120 120 Note: The ratios may be different for each load current rating 120: 1 115: 1 110: 1 104: 1 66. 5: 1 63. 5: 1 60: 1 57. 5: 1

Line Drop Compensation VDROP S VIN FC 7 L I FC 9 SL R X VCOMP VOUT FC 8 FC 6 VCOMP = VOUT - VDROP R VR FC 4 X VX FC 5 Load Center