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Re: [TCML] MOT Measurements
Hi Finn, All (Ted, Herwig),
Finn, I went through Tera Ranta equations against my own and then ran
the simulations measuring the primary current with the secondary shorted
(a great test for accuracy). I simply changed the source voltage as
appropriate to the measurement and then changed the L1, L2, and K values
associated to the transformer as indicated by Tera's values and my own
(hope this table doesn't wrap or have formatting issues).
Freq Vin (m) Vout (m) L1 Ios (m) L1 Isc (m) L2 Isc (m) Winding
Ratio Vout (calc) Inductance Ratio (calc) L1 Reactance (calc) Bart
L1 (calc) Bart L2 (calc) Tera L1 (calc) Tera L2 (calc) Tera k
(calc) Bart k (calc)
60 10.14 182 0.178 1.72 0.096 18 182.52 324 57.0 0.1511
48.96 0.1511 48.59 1.001 0.947
60 20.00 365 0.220 3.31 0.150 18 360.00 324 90.9 0.2411
78.13 0.2411 97.11 0.909 0.966
60 30.20 563 0.270 5.00 0.240 18 543.60 324 111.9 0.2967
96.13 0.2967 115.23 0.946 0.973
60 40.20 747 0.310 6.62 0.320 18 723.60 324 129.7 0.3440
111.45 0.3440 132.23 0.948 0.976
60 50.10 928 0.360 8.42 0.410 18 901.80 324 139.2 0.3692
119.60 0.3692 140.42 0.950 0.978
60 60.20 1123 0.430 10.63 0.530 18 1083.60 324 140.0 0.3714
120.32 0.3714 138.94 0.964 0.980
60 70.20 1321 0.510 13.46 0.680 18 1263.60 324 137.6 0.3651
118.30 0.3651 136.00 0.975 0.981
60 80.00 1476 0.600 16.60 0.860 18 1440.00 324 133.3 0.3537
114.59 0.3537 125.95 0.978 0.982
60 90.10 1681 0.780 24.00 1.120 18 1621.80 324 115.5 0.3064
99.28 0.3064 122.50 0.933 0.984
60 100.00 1812 0.980 29.00 1.320 18 1800.00 324 102.0 0.2707
87.70 0.2707 107.75 0.908 0.983
60 110.10 1971 1.600 36.00 1.600 18 1981.80 324 68.8 0.1825
59.14 0.1825 73.52 0.892 0.978
60 120.20 2071 2.760 43.00 1.880 18 2163.60 324 43.6 0.1155
37.43 0.1155 45.53 0.868 0.967
Above is the measured and calculated values. Note that both Tera and I
calc L1 the same in all cases, but L2 changes. Note that k is very
different also. This is how the the simulation resulted using Tera' L
and k values and my own against real measurements:
Tera (L1 current w/L2 shorted) Bart (L1 current w/L2 shorted) Actual
Measured Value
24.149 1.693 1.72
1.217 3.254 3.31
2.519 5.016 5.00
2.998 6.476 6.62
3.624 8.2 8.42
6.553 10.77 10.63
10.24 13.43 13.46
13.67 16.66 16.60
5.85 24.3 24.00
5.34 28.72 29.00
7.58 36.21 36.00
10.92 42 43.00
This is why I am extremely confident in both measurement methods and
calculations regarding the transformer. There is no way in hell that my
calculations could possibly be as close as they are to real measured
values in primary current under shorted conditions unless the
transformer model was correct (this means k, L1, and L2 are real).
Tera Ranta's equations do not work. It was a great attempt, but it isn't
right (worse than I expected actually). His coupling addition for the L2
equation and coupling itself is where his problem is located.
Just in case the above tables are unreadable due to formatting, here is
my spreadsheet:
http://www.classictesla.com/temp/TeraRanta-Bart.xls
Everyone can run the simulations themselves. A simple AC source input at
posted AC values, a linear transformer, Rp and Rs of the transformer.
Here's a gif of a simple simulator run that identifies source,
transformer values, shorted secondary, and where the primary current is
inserted. It doesn't get much simpler than this (Microsim).
http://www.classictesla.com/temp/MOT.gif
Take care,
Bart
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