Variable Capacitor
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Air Variable Capacitor 10-50pf. 2KV $6.99 |
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Air Variable Capacitors lot of 5 $4.99 |
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Variable Capacitor 15pF to 260 pF $5.00 |
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Variable Capacitor Dual 10pF to 40 pF $5.00 |
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Variable Capacitor $2.00 |
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Variable Capacitor 10 pF to 110 pF $5.00 |
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Variable Capacitor 10 pF to 50 pF $5.00 |
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Variable Capacitor 10 pF to 60 pF $5.00 |
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Variable Capacitor 30 pF to 230 pF $6.00 |
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Variable Capacitor 5 pF to 50 pF $5.00 |
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Variable Capacitor 5 sections 25 pF to 480 pF $8.00 |
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Variable Capacitor Dual 5 pF to 40 pF $5.00 |
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Variable Capacitor Dual 7 pF to 25 pF $5.00 |
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Variable Capacitor 25pF to 290 pF $5.00 |
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Variable Capacitor 10pF to 160 pF $5.00 |
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Variable Capacitor Neutralizing $5.00 |
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5 HAM RADIO AMPLIFIER VARIABLE CAPACITORS EF JOHNSON CARDWELL MILLEN $15.15 |
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Variable Capacitor 15 pf to 60 pF $5.00 |
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Variable Capacitor 6 pf to 140 pF $3.00 |
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Variable Capacitor 6 pf to 150 pF $3.00 |
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Variable Capacitor 5 pf to 60 pF Lot of 4 $5.00 |
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High Voltage Air Variable Capacitors 22-360pF- Amplifier/Turner REPAIR DIY $20.00 |
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VARIABLE AIR CAPACITOR WITH CONTROL KNOB LOCK $4.99 |
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Jennings UCS-300-10S 10-300PF 10KV Vacuum Variable Capacitor $195.00 |
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Trimmer variable capacitor 918-0006-00 Collins KWM-2 S-line 32S $20.00 |
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NATIONAL TYPE DX VARIABLE CAPACITOR $50.00 |
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2 pcs Variable Capacitor with gear drive NOS $12.00 |
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Variable Capacitor with gear drive NOS 1 pcs $5.70 |
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Jennings 12 to 1000pf 15kv Vacuum Variable Capacitor $552.93 |
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Jennings 50 to 2000pf 12KV Vacuum Variable Capacitor $631.92 |
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Jennings UCS-300-10S 10-300PF 10KV Vacuum Variable Capacitor $195.00 |
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Air Variable trimmer capacitor. 2.9 – 70 pF $7.87 |
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Dual 285pF plastic Variable Capacitor Total 570pF Oty:4 $8.95 |
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x8 Russian Variable Trimmer Air Capacitor 1KP6 2.8-12pF 650V $9.95 |
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x8 Russian Variable Trimmer Air Capacitor 1KP2 2.2-15pF 300V $9.95 |
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x8 Russian Variable Trimmer Air Capacitor 1KP3 1.8-9pF 300V $9.95 |
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x8 Russian Variable Trimmer Air Capacitor 1KP4 1.8-6.5pF 300V $9.95 |
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x8 Russian Variable Trimmer Air Capacitor 1KP7 2-6.5pF 650V $9.95 |
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Air variable capacitor 2 x 245 pF 1 pcs NOS $7.00 |
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x8 Russian Variable Trimmer Air Capacitor 2KP3 1.5-5.8pF 350V $9.95 |
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DOUBLE VFO VARIABLE TURNER CAPACITOR DIAL 10 30 PF $9.95 |
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Air Variable capacitors Ceramic coils inductors shaft coupling ham radio $25.00 |
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Dual Gang Variable Capacitor, Crystal Radio, Ham, NOS $3.90 |
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PISTON VARIABLE CAPACITOR 0.6-3.5pf SIEMENS NEW V42246 Z2 A4 $1.95 |
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300 PF Variable Capacitor *Free Shipping $11.96 |
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280 PF & 500 PF In One Variable Capacitor *Free Shipping $19.96 |
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300 PF Variable Capacitor *Free Shipping $11.96 |
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53 PF Variable Capacitor *Free Shipping $11.96 |
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365pf Single Gang Air Variable Tuning Capacitor Crystal Tube Ham Radio $15.99 |
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Air variable capacitor 2 x 245 pF 2 pcs NOS $14.00 |
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National Dual Section Variable Capacitor 100pF at 6KV $20.00 |
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EF Johnson Dual Section Variable Capacitor 151pF, 7KV $20.00 |
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HAMMARLUND FT-86 100 Pf 3.5KV AIR VARIABLE CAPACITOR AMPLIFIERS ANTENNA TUNER $23.00 |
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Variable capacitor 2 x 245 pF 1 pcs NOS $7.00 |
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Vacuum Variable Capacitor 4-100pF 5kV New in Box! $109.50 |
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NOS VINTAGE HAMMARLUND MC-100-S AIR VARIABLE CAPACITOR 100pF HAM RADIO $9.00 |
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VARIABLE CAPACITOR 36 TO 150 PF PERFECT FOR ANTENNA TUNER OR AMP $14.95 |
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Miniature 2 Gang Variable Tuning Capacitor for AM Band $4.95 |
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Ceramic Military Trimmer Variable Capacitor 4-15pF Qty:16 NEW $7.95 |
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Air variable capacitor 3×430 pF 1 pcs $9.95 |
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Air variable capacitor 2×350 pF 1 pcs $9.00 |
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Air Variable Capacitor lot of 5 $9.99 |
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Bud Air Variable Capacitor 9KV $15.98 |
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5 GANG VARIABLE AIR CAPACITOR TRONSER QUALITY! 4~73PF CUSTOM MADE UNIQUE PRODUCT $31.60 |
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Vacuum Variable Capacitor 4-100pF 5kV $89.50 |
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Vacuum Variable Capacitor 20-1000pF 10kV kp1-4 New in Box ! $199.50 |
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Used Jennings UCSA-525 Vacuum (Variable?) Capacitor $15.50 |
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3 section variable capacitor 14-367 pf and 12-293 pf X 2 $13.95 |
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Air variable capacitor 100 pF with gear & scale 1 pcs $6.00 |
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15 65 PF METAL CERAMIC AIR VARIABLE CAPACITOR 7761569-5 $14.95 |
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NIB 56 pf air variable capacitor Lot of 4 $14.50 |
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HIGH VOLTAGE, 5 kV AIR VARIABLE CAPACITOR 20-220 pF $110.00 |
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1000pF Total Variable Tuning Capacitor for Crystal Set Radio 6:1 Reduction Drive $15.72 |
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Mini 4 Gang Poly-film Variable Tuning Capacitor 320pF. Great for Crystal Radios $5.95 |
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HV variable capacitor 15 – 77 uuf / pf / high voltage cap $14.95 |
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2 GANG VARIABLE AIR CAPACITOR ALPS HQ! WITH BRACKET,BESTSELLER OVER THE GLOBE! $9.48 |
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10-1200 pF/4kV Vacuum Variable Capacitor KP1-12 New in Box ! $199.50 |
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National Radio STD-50 dual section 50pf variable capacitor NIB, 1400V $12.95 |
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YAESU FT-101B HAM RADIO PARTS – variable capacitor TC27 $19.95 |
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Variable Capacitor 9-50pf NPO brass-aluminum construction for no drift VFO etc $10.95 |
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Cardwell 154-14 100pf 4500V variable capacitor $44.95 |
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Double Air Variable Capacitor 5-30pf EACH $4.00 |
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x1 2-Gang Variable Air Capacitor 10-500pF $12.95 |
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7,5-350pF 10kV 50A HF Vacuum Variable Capacitor. New in Box ! $139.50 |
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HAMMARLUND AIR VARIABLE CAPACITOR 5-28pF,LONG SHAFT 4-3/4″,HAM RADIO PART $7.99 |
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(6) 12~180 pF Variable Capacitors [Adjustment types: 4-Vertical 2-Hoizontal] $9.95 |
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(2ea) 1/4″TUNING SHAFT COUPLER (U-JNT) FOR VARIABLE CAPACITOR . FREE SHIP US 48 $8.95 |
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Johnson variable Capacitor part #N5910-678-4350 (NIB) $75.00 |
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Fast Tuning Vacuum Variable Capacitor 10-35pF 10kV New! $109.50 |
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Mounting Bracket for Vacuum Variable Capacitor (50mm) $33.35 |
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Vacuum Variable Capacitor 10-200pF 25kV NEW IN BOX ! $159.50 |
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Russian Variable Air Capacitor 5-75pF Lot of 2 NIB $8.95 |
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x10 Russian Variable Air Capacitor 5-75pF NIB $38.95 |
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Jackson C803 Variable Trim Capacitor 100pF Ham Hobby Radio $18.96 |
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Philips – 6pF – 80pF 10mm Variable Trimmer Capacitor -8pcs $3.22 |
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Vacuum variable capacitor 25-500 pf 10 kV Jennings $220.00 |
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x8 Russian Variable Trimmer Air Capacitor 1KP1 2.8-24pF 300V $9.95 |
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Poly Film Variable Tuning Capacitor For Broadcast Band 265pF: New $4.95 |
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5 PF Variable Capacitor *Tested on HP *GI Corp Brand $7.96 |
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2 170 PF Variable Capacitors *One Unit *RC Brand $7.96 |
Tariffs And Energy Management
TARIFFS AND ENERGY MANAGEMENT
1a) Discuss briefly the factors governing tariff structures.
The tariff structure of energy is governed by the factors:
Demand
The demand level of energy will determine the tariff structure of energy, when the demand is high the tariff is likely to be low and when the demand is low the tariff is likely to be high.
Rate
The rate charge of unit consumption of energy will also determine the structure of energy tariffs; the rate is the unit charge of one unit of energy consumed.
Distribution voltage
The distribution voltage will also determine the structure of energy tariff when the distribution voltage is high then the tariff is likely to be high.
User application:
The other factor that determines the structure ids the user application, this is whether the consumption is for domestic application or for industrial or commercial purposes.
Accounting methods
The other determining factor is the accounting method used in determining the consumption level of electricity, the most used application of determining the consumption level is the use of electric meters that determine the watt consumption level over a period of time.
Social and economic factors:
The structure of energy tariff will also be determined through considering the social and economic factors in a region, the adoption of a certain structure will take into consideration other factors of a region.
1b) Describe a typical tariff for:-
i) domestic consumers
The domestic consumer will pay for the number of units consumed per month, these charges may include a monthly standing charge, for example the rate will be charged per KWH, for example a domestic consumer may be required to pay a twenty dollar standing charge and in addition to this pay 40 cents per KWH. The tariff will also change in terms of peak and off peak consumption, peak units will be charged higher than off peak.
ii) industrial consumers
An industrial consumer will still pay a standing monthly charge if applicable, he will also be required to pay for the number of units consumed per month, for industrial consumption of energy the consumer will pay less due to bulk consumption than the domestic consumer, peak charges will be higher than the off peak charges and summer tariffs will also be different from the winter charges where winter charges will be higher than the summer tariffs.
2) A factory with a foundry and a machine shop has a maximum demand of 750 kW and a load factor of 0.2. The tariff is 20 Pound/kW of maximum demand + 4 Pence/kWh of energy consumed.
a) Calculate the annual cost of electricity.
Load factor = (KWH/ total KWH) X 100
0.2 = (750/ Y)
Y= 3750
Total consumption = 3750
Cost = 3750 X .04 = 150
Cost for maximum demand 750 X 20 = 15000
Total cost = 15000 +150 = 15150 pounds
b) Discuss briefly one way in which the energy cost of the factory may be reduced without reducing the number of kWh consumed.
Because most of tariffs are charged higher during peak hours then the firm may reduce the cost of energy by utilising the off peak hours when the tariffs are lower. Lower energy costs can also be achieved by reducing the load factor of the firm, if the firm achieves a lower load factors then the cost of energy will be lower which can be achieved without reducing the number of KWH consumed.
3a) State one method of raising the overall power factor of an industrial load.
Use of an power corrector either passive or active (PFC)
3b) Discuss briefly the advantages and disadvantages of applying power factor correction at:
i) the main bus bars
Advantage:
It is a useful method in power factor correction
The use of a filter can reduce the harmonic current
Disadvantage:
The rectifier used in this case is non linear and therefore there is energy at the harmonics of the frequency of the input current.
The above problem also posses a problem to the energy providing company as they cannot rectify this problem, whereby they cannot use capacitors to rectify the harmonic current
ii) individual loads
Advantages:
It is a useful method inpower factor correction
It is easy to adjust the correction level because the correction acts as a variable capacitor
Disadvantages:
It is not cost effective as it requires the installation on each load or machine
4) A factory has maximum demand of 400 kW at a lagging power factor such that 600 kVAr of re-active power has to be supplied.
The tariff in operation includes a maximum demand charge of 12 Pound/kVA.
Consider the effect of adding capacitor banks to the system in SIX stages, each drawing 100 kVAr leading. The capital charges on each 100 kVAr bank are 400 Pound per annum.
a) Calculate the net saving and overall power factor at each stage.
Power factor = real power (p) watts/ apparent power (s) volt amperes
S2 =P2 + Q2
Where Q is the reactive power measured in VAR
initial
stage 1
stage 2
stage 3
stage 4
stage 5
stage 6
reactive power Q
600
500
400
300
200
100
0
Q2 ( Q X Q)
360000
250000
160000
90000
40000
10000
0
P
400000
400000
400000
400000
400000
400000
400000
P2
160,000,000,000
160,000,000,000
160,000,000,000
160,000,000,000
160,000,000,000
160,000,000,000
160,000,000,000
S2
160,000,360,000
160,000,250,000
160,000,160,000
160,000,090,000
160,000,040,000
160,000,010,000
160,000,000,000
S
400000.45
400000.3125
400000.2
400000.1125
400000.05
400000.0125
400000
power factor
0.999998875
0.999999219
0.9999995
0.999999719
0.999999875
0.999999969
1
power save
0
0.137499869
0.249999797
0.337499763
0.39999975
0.437499747
0.449999747
savings
0
1.649998427
2.999997562
4.049997153
4.799997
5.249996965
5.399996962
per year savings
0
593.9994338
1079.999122
1457.998975
1727.99892
1889.998907
1943.998906
b) Plot a graph of net saving (vertically) against overall power factor (horizontally)
c) Explain what your results and graph show.
From the above graph it is clear that as we increase the number of bank capacitors the reaction energy is reduced until it is zero, the firm makes a save on their cost of energy as shown above.
5) Energy-efficient lamps are miniature fluorescent lamp designed to replace ordinary GLS lamps.
a) Discuss briefly the advantages and disadvantages of energy-efficient lamps compared with other sources of illumination.
Advantages of miniature fluorescent
They consume less energy than GLS lamps
Longer life span
Disadvantages of miniature fluorescent
Costly to install and maintain
Cannot be used at low voltages
Do not lender desired colour
Advantages of GLS lamps
Cheap to install and maintain
They lender good colour
Simple to operate
Disadvantages of GLS lamps
Consume more energy
Short life span
b) Obtain manufacture’s data and compare the total cost of using an energy-efficient lamp with that of an ordinary GLS lamp, assuming illumination is provided for 8000 hours.
GLS cost in pounds
Florescent cost in pounds
initial cost
2.8
9.3
power consumption watt
100
7
voltage
240
240
per hour
0.41666667
0.029166667
constant 10
4.16666667
0.291666667
8000 hours
33333.3333
2333.333333
total cost
33336.1333
2342.633333
References:
Electricity bulbs (2007) advantages and disadvantages of GLS and florescent, retrieved on 13th October
The E Shops(2007)bulb prices, retrieved on 13th October
Lewis Evans (2006) Alternating Currents, Victoria University Press, New Zealand
About the Author
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Power Tip #24: Convert parallel impedances to series impedances
Understand how impedance-topology conversion can simplify transformer equivalent circuits or filter networks Series and parallel circuits – Transformer – Sincil Bank – Rangers F.C. – Battery
