Voltage Regulators
Outline
•
•
•
•
•
•
Regulator Function & Purpose
What is inside
Neutral Position
Nameplate
Bypassing
Basic Control Settings
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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
12am
6am
12pm
TIME OF DAY
6pm
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

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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 = 100V
Vp = 1000V
-
-
10:1
Step-Up Autotransformer
+
+
Vs = 1100V
Vp = 1000V
-
-
Step-Down Autotransformer
+
+
Vp = 1000V
-
-
Vs = 900V
Step Regulator
N
+
-
8
7
6
5
4
3
2
1
+
Step Regulator with
Revsersing Switch
N
+
-
8
7
6
5
4
3
2
1
+
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
Bypass Switch
Source
A
N
Disconnects
L
S
Series
Lightning
Arrester
SL
Shunt
Lightning
Arrester
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
RCT2
RCT1
V6, V1, & C
switches
TB2
TB1
Optional FO-RS232 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
Star
t
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
LDis
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 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
SVR
SVR
TD = 45 SEC
TD = 75 SEC
SVR
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=0 c=10 c=0
30 sec. outof-band
121.0
2 sec delays
(horizontal)
in-band
120.0
time
119.0
UBE
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=0 c=10 c=4.5
121.0
2 sec delays
(horizontal)
25.5 sec.
out-of-band
in-band
120.0
time
UBE
SV
LBE
119.0
10 sec. out5 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
c=30
tap changes
w/no 2 sec.
delay between
taps
out-of band
121.0
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
E1
E1
E1
E1
E2
E2
E2
E2
INTERNAL
R.C.T.
TEST
OVERALL
P.T.
TAP
TERMINAL
POT.
RATIO
(CONTROL) VOLTAGE
RATIO
120:1
120:1
120:1
120:1
60:1
60:1
60:1
60:1
120
115
110
104
133
127
120
115
120
120
120
115
120
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
L
S
VIN
FC 7
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