Current Transformer
A look at what is currently available on eBay
 Measuring Range 0.1-80A Current Transformer TA1610P New US $6.50 
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 Epoxy Resin Embedding Current Transformer TA1410-02 US $7.45
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 100/5 Current Transformer For AMP Meter Gauge US $9.99
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 1000/5 Current Transformer For AMP Meter Gauge US $119.99
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 5.8mm Diameter Shot-hole Current Transformer 0.1-80A US $6.08
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 Blk 10VA Power Split Core Current Transformer 400A:0.1A US $61.86
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 0.5 Accuracy Class 30/5 Current Transformer 0.66KV New US $13.71
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 3.5mm Output AC Current Sensor Transformer SCT 013-030 US $13.84
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 0.5 Accuracy Class 5VA 0.6KV 250/5 CT Current Transformer US $24.49
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 20/5 Current Transformer For AMP Meter Gauge US $9.99
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 200/5 Current Transformer For AMP Meter Gauge US $19.99
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 300mA Constant Current 18x1W LED Driver Transformer DC 30V-60V 300mA US $10.41
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 5A-200A 0.333V Split Core Current Transformer SCT-019 US $24.08
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 0.5 Accuracy Class CT Current Transformer 50/60Hz 1000/5 US $36.12
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 0.5 Accuracy Class CT Current Transformer 50Hz 1000/5 US $54.65
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 SCT-013-000 Non-invasive AC Current Sensor Transformer US $14.05
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 300/5 Current Transformer For AMP Meter Gauge US $29.99
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 TV19 Current Type Voltage Transformer 0-5mA Input Blue US $6.65
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 20mA Output 8V Mutual Inductor Current Transformer Red US $7.87
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 50/5 Current Transformer For AMP Meter Gauge US $9.99
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 500/5 Current Transformer For AMP Meter Gauge US $59.99
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 Pin Mounting Electronics Phase Current Transformer US $5.41
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 5VA Rated Load Current Transformer w Installing Parts US $15.45
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 5mA Output Leading Wire Type Current Transformer Red US $5.17
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Electrical Engineers, How do I determine the needed primary current flow in a transformer?
Say you just bought a transformer off the shelf of a hobby store and you need to determine if the primary winding needs a load resistor, or what the primary current would be to get the highest efficiency.
What steps and or calculations do you have to do to ensure the transformer operates within it's range but at the highest efficiency?
The primary windings never need a resistor across them. I think a transformer is rated in either output Watts or Volt Amps. If you keep the load within the rated output Volt Amps of the transformer then the transformer`s primary current will take care of it`s self. A transformer`s primary current is determined by the transformer`s secondary current (load current) and it`s turn`s ratio
Ideally If a transformer has zero secondary current it will also have zero primary current. This just means that when an ideal transformer is not transferring any power it is also not using any power from the ac input Voltage.
The transformer specifications should tell you at what output operating Volt Amps the transformer is most efficient.
To ensure that the transformer will not operate when overloaded you can calculate the transformers maximum allowable output current by dividing it`s rated output Volt Amps by it`s output Volts. After determining the maximum allowable output current then you can place a fuse of that value or slightly higher in series with the output windings of the transformer.
The only way to ensure that the transformer operates at it`s highest efficiency is to select a load whose Volt Amp extremes never vary outside the range of the maximum efficiency Volt Amps of the output of the transformer.
Items recently purchased from this site
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CURRENT TRANSFORMER 400-600 AMPS CG388B 600 VOLTS MAX, WET LOCATION ELEC BOX W/ 2 CURRENT TRANSFORMERS 400-600 AMPS 600 VOLTS MAX , CUTLER HAMMER D60LT4 CURRENT TRANSFORMER 600V A2 ( LOT OF 24), SQUARE D DISCONNECT CAT#H365 400A 600V 3 PHASE FUSED W/ CURRENT TRANSFORMERS, Westinghouse Current Transformer 300:5 3486C98H03 , Cutler Hammer Current Transformer 4601B05H16 4:1 , Eaton C311CT Current Transformer 500:1 Ratio ! WOW !, ABB SCV INDOOR METERING/PROTECTION LOW VOLTAGE CURRENT TRANSFORMER CT400A!!!, AC Motor Load Surveyor Power Reporter PMT PRM Esterline Angus Current Transform, CURRENT TRANSFORMER AMPTRAN CT-50 AMPROBE RECORDER, Cutler Hammer D60LT3 Current Sensing Relay Transformer, WESTINGHOUSE ECT-5 CURRENT TRANSFORMER 254A586G11, Current Transformer 210R-302 3000:5 Square D NOS, SANGAMO CURRENT TRANSFORMER CAT# 71689 .... 3000:5A *64A, Simpson 3 Phase Panel Mounted Power Meter & Current Transformer 200-1-1-1-0, GE JKM-5 Current Transformer 200/400:5 755X42G43 Tested before shipping warranty, MWB Z-68-887 TRANSFORMER CURRENT S-N 85-833432 MWB, K-Tec Current Transformers WKE-130 & WKE-200 working, Current Transformer 422D295-G01 Westinghouse, TEKTRONIX CT-5 HIGH-CURRENT TRANSFORMER AND DC COIL!, INSTRUMENT CURRENT TRANSFORMER CTW3-60 200:5 TO 600:5A, TEKTRONIX CT-5 HIGH-CURRENT TRANSFORMER!, LOT (3) 121 ASTRA Current Transformer 1200:5A Type AB, Current Transformer 203R-162 1600:5 Square D NOS, JOSLYN ITE K-1600 OPTI-TRIP II RMS TRIP UNIT MANUAL RESET & CURRENT TRANSFORMERS, 25 kV Sub-Station CT CURRENT TRANSFORMER - Ratio 200:5, 4 CURRENT TRANSFORMERS 120-601 - 600V -10KV- USED $399, Fedcor First Electro Dynamic Corp. 98 Current Transformer, Ohio Semitronics Current transformer P/N 12975 200:5 RF 2.0 New IN Box, Ohio Semitronics current transformer 12973 Ratio 100:5 RF 2.0 New in Box, General Electric 785-201 Current Transformer , Square D S33926 Neutral Current Transformer Kits, NEW!, ACME MODEL TA2-81203 CURRENT TRANSFORMER 3000VA NEW, SQUARE D 140R-502 TRANSFORMER CURRENT 5000:5 RATIO, SQ D Part #S33925 Neutral Current Transformer , Square D S34036 Neutral Current Transformer 400-1600A, 600:5 Ratio Three phase current transformer , Square D Netural Current Transformer 34036 1000-4000A, Neutral Current Transformer For MasterPact Square D Breakers Part# S34036, RELIANCE - CURRENT TRANSDUCER / TRANSFORMER Full Scale 2 kA / 40mA DC 64670-21R, JOSLYN ITE K-225 OPTI-TRIP II RMS TRIP UNIT, MANUAL RESET & CURRENT TRANSFORMERS, INSTRUMENT TRANSFORMERS 780-401 FULLY ENCLOSED 400A CURRENT TRANSFORMER!, NIB KUHLMAN INDOOR AUXILIARY CURRENT TRANSFORMER A1508140-570 ACT-645 , NEW SIEMENS NGSL400 VL NEUTRAL CURRENT TRANSFORMER JG LJ 400A 400 AMP, NEW GE/INSTRUMENT CURRENT TRANSFORMER 144-202 2000:5, MERLIN GERIN GROUND FAULT NEUTRAL CURRENT TRANSFORMER (CK1200) NEW , Rare Find Weston Current Transformer Model 327 NOS Mint, New* Allen Bradley 140307-7 LEM LC500-S/SP/6 Current Transformer 1:3000 9V /270, Allen Bradley X-241563 X241563 Current Transformer 300/5 A, ITI Current Transformer 622-601 600:5A , ITI Current Transformer 139-601 600:5A , General Electric 641X92 Current Transformer NEW-NO BOX, Dranetz TR2022 Current Transformer 10 to 1000 Amps AC,
April 26th, 2007 in
Uncategorized | tags: current, current transformer, current transformer basics, current transformer circuit, current transformer design, current transformer polarity, current transformer ratio, current transformer saturation, current transformer theory, current transformers, electricity, electronics, power, transformer, transformers