How should I increase signal level with a transformer?

[xzswq21]

Hello
it's very odd, but when I simulate the following circuit I don't get the right voltage at the output! why? the output should be sqrt(Ls/Lp)*Vin=sqrt(20/1m)*50=7071 V ,but the output is only 2.11 Kv


I have attached the LTspice file.  trans_1.asc (0.94 kB - downloaded 35 times.)

Actually I have a 50V sine wave, I want to apply it to a transformer to produce a 5KV sine wave.
could you please help me to solve this odd problem?

[Ian.M]

You are measuring it wrong.  Change the .tran command to .tran 0 200m 100m 100u to start saving data after the initial transients have settled, then paste this as a directive:

Code: [Select]

.meas HV_1 RMS V(HV_1)
.meas n002 RMS V(n002)
.meas turns_ratio param HV_1/n002
.meas ind_ratio param turns_ratio**2
.error ; force Error Log display
n002 is the top end of L1.
Results:

Code: [Select]

hv_1: RMS(v(hv_1))=4216.57 FROM 0 TO 0.1
n002: RMS(v(n002))=29.8156 FROM 0 TO 0.1
turns_ratio: hv_1/n002=141.421
ind_ratio: turns_ratio**2=20000
which is exactly as expected.

N.B. There is a considerable voltage drop and phase shift due to R1.