Download Capacitor Training - Duck River Electric Membership Corporation

Capacitor Training
Duck River Electric Membership Corp.
Doug Simpson

CAPACITOR FUNDAMENTALS

CAPACITOR USES

DREMC Practices

Capacitor Safety
Welcome and Introduction
A capacitor is a device that accepts an
electrical charge, stores it, and then
releases the charge when desired.
 A good comparison to a capacitor would
be a battery.

CAPACITOR FUNDAMENTALS
When talking about Capacitors…
 KVAR - is the “measure of” good offset a
capacitor will provide against bad
inductance. It is not the name for a
Capacitor, only a measurement.
 The term Bank refers to each phase being
involved just like with a transformer bank,
A,B, & C.
CAPACITOR FUNDAMENTALSVocabulary
In its simplest form, a capacitor consists
of two metallic plates separated by an air
gap.
 Only three factors govern how much
energy can be stored in a capacitor.
1. How big are the plates?
2. How close are they together?
3. What insulating material separates
them?

CAPACITOR FUNDAMENTALSWhat does a Capacitor consist of?
Basically, the larger the surface of the
metallic plates and the closer they are
together, the more energy the capacitor
can store.
 If the space between the plates is filled
with different insulating material, such as
Kraft paper or oil, the capacity will be
greater than with air.

CAPACITOR FUNDAMENTALS-
What a Capacitor consists of continued…
Improving Power Factor (or VAR
Control).
2. Reducing Line Losses (or VAR Control).
3. Decreasing Voltage Drop.
1.
DREMC uses Capacitors for VAR control on
our system, not decreasing voltage drop.
CAPACITOR USESWhat are the Primary uses for a
Capacitor?
Real power is usable power measured as kW(kilowatt).
Reactive power is the unusable power measured as
kVAR (kilo Volt Amp Reactive).
Apparent power is the true measured value on the
power system measured as kVA(kilo Volt Amp). It is
made up of two components, real power (expressed
in kW) and reactive power (expressed in kVAR).
(kW)
(kVAR)
CAPACITOR USESPower Factor
P=
(kW)
Q=
(kVAR)
kW² + kVAR² = kVA²
P² + Q² = S²
a² + b² = c²
To understand what a capacitor does, you
will have to understand what is meant
by POWER FACTOR (pf).
Pf= Real Power(kW) =
1 (Ideal Case)
Apparent Power(kVA)
CAPACITOR USESPOWER FACTOR…
Pf=
Real Power
Apparent Power
=
1 (Ideal Case)
Reactive Power
Real Power
CAPACITOR USESPOWER FACTOR Continued…
Imagine yourself at Point A wanting to get
to Point C, but due to obstructions you
must first walk to Point B and then to
Point C. The energy you expended walking
to Point C was increased because you
could not take the direct course.
CAPACITOR USES- Line Losses and Voltage Drop
Power Systems act just like our example. The
reactive power ( the extra steps from Point B to
Point C) makes the power system work harder. To
offset the this reactive power, capacitors are
added to the system to make Points B and C
closer together. This makes the apparent power
value closer to the real power value. Remember,
the Ideal case is for the apparent power and the
real power to equal each other. This would make
the power factor equal 1.
CAPACITOR USES- Line Losses and
Voltage Drop Continued
1. Equipment may have to work harder and will
not last as long because of line losses.
Capacitors help the equipment work better
because the equipment is not overburdened
and, in turn, will last longer
2. High kVAR demands cause excessive voltage
drop. Capacitors help to correct this.
3. A low power factor may cause an unnecessary
increase in system losses. Remember the ideal
power factor is 1.
CAPACITOR USES- Line Losses and
Voltage Drop Continued
FIXED BANKS- The Capacitor bank stays
“online” all the time and should have
operable load break fuse disconnects.
 SWITCHED BANKS- On a circuit are
switched as TIME/VOLT. This means the
Capacitor bank switches on and off by
TIME and can be over ridden by VOLTAGE
either too high or too low. They must
have operable “oil switches” on these
banks.

DREMC Practices
CAPACITOR BANK TYPES
Fixed Capacitor Bank
Switched Capacitor Bank
Load Break Fuse
Disconnect
“Oil Switch”
(Vacuum)
DREMC Practices
CAPACITOR BANK TYPES

SUBSTATION SWITCHED BANKS-
Are switched at the Manchester 161 by a
S&C Intellicap only on voltage at 8,100
kVAR each bank, switches 318 and 328.
 Are switched at Unionville by a SEL relay
on Power Factor normally and on VOLT
when the Mobile is in service, because it
does not have a LTC, at 1,800 kVAR each
bank, switches 318, 328, 338, & 348.

DREMC Practices
CAPACITOR BANK TYPES

DREMC stocks 100 kVAR and 200 kVAR
capacitors

A 600 kVAR bank means that A, B, & C Ø
each have one 200 kVAR capacitor
mounted in the capacitor rack. 200 kVAR
times 3 phases = 600 kVAR
DREMC Practices
CAPACITOR BANK SIZE MATH

When Fusing both bank size and voltage
will influence your proper choice.
7.2kV, 300kVAR bank= 20T fuse
 7.2kV, 600kVAR bank= 40T fuse
 14.4kV, 600kVAR bank= 20T fuse
 14.4kV, 1,200kVAR bank= 40T fuse

DREMC Practices
Bank Sizes and Proper Fusing
When manually opened or closed, the
control will delay the intended action
for a total of 30 seconds. USE THIS
TIME TO GET IN A SAFE POSITION.
2. When opened automatically or
manually, the control will block
closing for 5 minutes total.
1.
DREMC Practices
S&C Intellicap Operation Features
1)
2)
3)
4)
5)
DANGER READ!
OPEN CAPACITOR SWITCH.
OPEN MAIN FUSES WITH AN
INSULATED STICK.
WAIT 5 MINUTES.
AFTER 5 MINUTES, BLEED OFF
CAPACITORS TO GROUND USING AN
INSULATED STICK.
JUMPER BOTH BUSHINGS TOGETHER
AND THEN TO TANK.
Capacitor SafetyProcedure
•
ALWAYS Ground the Capacitor with a
heavy wire jumper from bushing to
bushing to TANK to keep the
capacitor SHORTED for SAFETY!
•
Do not lift the capacitor by the
bushings or shorting wire to keep
from breaking the bushings for safe
handling.
Capacitor SafetyHandling Procedures
•
•
ALWAYS utilize load break devices
when removing a capacitor bank from
service.
USE A LOAD BUSTER TOOL WHEN
YOU CAN FOR ANY MALFUNCTIONED
LOAD BREAK DEVICE ON A
CAPACITOR BANK, DO NOT ATTEMPT
TO BREAK LOAD OTHERWISE!
Capacitor SafetyRemoving From Service