Square Loop Cores

Saturable reactors are e. g. used to stabilize output voltages of switched mode power supplies, to supress voltage spikes, to limit the current raise time of power switches or in pulse compression circuits to increase the current raise time.

Amorphous and nanocrystalline cores are especially suitable for such applications as they combine - after an accordant annealing treatment - a square hysteresis loop with low core losses.

The best known application for square loop cores are Magnetic Amplifier chokes in switched mode power supplies. They are highly effective in the regulation of high current - low voltage outputs.

Tape-wound cores VITROVAC® 6025 Z

Magnetic Amplifier chokes have been one of the first commercial applications for amorphous Co-based materials like VITROVAC® 6025 Z more than 3 decades ago. Due to their low core losses and the excellent squareness of the hysteresis loop, they widely replaced the formerly used permalloy alloys and have become popular world-wide.

In the table below standard cores sizes for Magnetic Amplifier chokes are listed. In case you need other sizes just give us a call.

 

 

Standard series MagAmp cores from VITROVAC® 6025 Z

Part number Nominal size Iron cross section Iron path length Core weight Saturation flux density Winding space Heat transfer factor
T60006-E40... da x di x h AFe lFe mFe (90°C) ACu Rth
  [mm³] [cm²] [cm] [g] [µWB] [cm²] [K/W]
10-W534 10 x 8 x 4 0,032 2,83 0,7 3,2 0,082 56
10-W663 10,1 x 6,9 x 4,5 0,058 2,67 1,2 5,8 0,059 57
10-W728 10,7 x 8,2 x 4,5 0,045 2,97 1,0 4,5 0,085 47
12-W464 12,8 x 9,5 x 3,2 0,042 3,5 1,1 4,2 0,121 44
12-W547 12 x 8 x 4,5 0,072 3,14 1,7 7 0,085 47
12-W535 12,5 x 10 x 5 0,05 3,53 1,4 5 0,14 42
14-W481 14 x 8 x 4,5 0,108 3,46 2,9 10,8 0,082 44
15-W813 15 x 10 x 4,5 0,09 3,93 2,7 9 0,121 37
16-W536 16 x 10 x 6 0,144 4,08 4,5 14,4 0,131 34
17-W537 17,5 x 12,5 x 6 0,12 4,71 4,4 12 0,231 30
19-W666 19,2 x 12,7 x 6 0,161 5,01 6,2 16,1 0,253 28
19-W539 19 x 15 x 5 0,08 5,34 3,3 8 0,33 27
19-W540 19 x 15 x 10 0,16 5,34 6,6 16 0,33 24
20-W538 20 x 12,5 x 8 0,24 5,1 9,4 24 0,206 26
25-W542 25 x 20 x 10 0,2 7,1 10,9 20 0,568 18
25-W541 25 x 16 x 10 0,36 6,44 17,9 36 0,36 19
30-W543 30 x 20 x 10 0,4 7,85 24,2 40 0,602 16
040-W544 40 x 25 x 15 0,9 10,2 70,8 90 0,98 11
040-W545 40 x 32 x 15 0,48 11,3 41,8 48 1,61

10

Tape-wound cores VITROPERM® 500 Z

Besides the amorphous VITROVAC® 6025 Z cores, nanocrystalline VITROPPERM® 500 Z cores have become popular in MagAmp circuits. Their advantages are lower material costs and a higher temperature stability against aging effects. However somewhat higher cores losses and a somewhat lesser squareness need to be considered in the design.

 

Standard series MagAmp cores from VITROPERM® 500 Z

Part number Nominal size Iron cross section Iron path length Core weight Saturation flux density Winding space Winding length Heat transfer factor
T60006-L20 da x di x h AFe lFe mFe (90°C) ACu lCu Rth
... [mm³] [cm²] [cm] [g] [µWB] [cm²] [cm] [K/W]
10-W759 10 x 7 x 4,5 0,054 2,67 1,1 11,9 0,059 2,27 57
11-W760 11 x 8 x 4,5 0,054 2,98 1,2 11,9 0,085 2,53 46
12-W761 12 x 8 x 4,5 0,072 3,14 1,7 15,8 0,085 2,53 46
12-W762 12,5 x 10 x 4,5 0,045 3,53 1,2 9,9 0,14 2,59 42
12-W803 12,8 x 9,5 x 3,2 0,042 3,5 1,1 9,3 0,121 2,26 44
16-W763 16 x 10 x 6 0,144 4,08 4,3 31,7 0,124 3,25 34
16-W764 16,5 x 12,5 x 6 0,096 4,56 3,2 21,1 0,231 3,3 30
17-W765 17,5 x 12,5 x 6 0,12 4,71 4,2 26,4 0,231 3,3 30
19-W766 19 x 15,2 x 4,5 0,068 5,37 2,7 15 0,323 3,28 27
20-W767 20 x 15 x 8 0,16 5,5 6,5 35,2 0,206 4,08 26
20-W768 20 x 12,5 x 8 0,24 5,11 9 52,8 0,206 4,08 26