Lake Shore Model 480 Fluxmeter User’s Manual
Service and Calibration
8-11
8.9.4 AC Peak Offset
1. Short the input terminals of the Model 480.
2. Set Model 480 to AC, Dual Peak operation, 100 k
Input Resistance, 30 mV·s range.
3. Set Model 480 units to Volts (available only through computer interface, send “UNITS 0” over the
computer interface).
4. Reset and read offsets directly as voltages on the Model 480.
5. Take 10 readings.
6. Average all positive readings, average all negative readings.
7. Send positive average reading to Range Voltage Offset locations 8, 9, 10, 11, 26, 27, 28, 29 from
the computer using the form “CALZERO <location #> <reading>“
8. Send negative average reading to Range Voltage Offset locations 14, 15, 16, 17, 32, 33, 34, 35
from the computer using the form “CALZERO <location #> <reading>“ (Include the “-” with the
reading.)
8.9.5 AC RMS and AC Peak Gain Calibration
The following procedure is to be repeated for each range entry in Table 8-1.
Table 8-1. AC Calibration Table
Range
Input R
Freq
Amplitude
Vs(nom)
CalRng#
Vs(pk)
Pk+Rng# Pk-Rng#
30 mV·s 100 k
60 Hz.
5.655 Vrms
15 mV·s
20
21.2 mV·s
26
32
3 mV·s 100 k
60 Hz. 0.7540 Vrms
2 mV·s
21
2.83 mV·s
27
33
300 µV·s 100 k
1 kHz.
1.257 Vrms 200 µV·s
22
283 µV·s
28
34
30 µV·s 100 k
1 kHz. 0.1257 Vrms 20 µV·s
23
n/a
n/a
n/a
3 mV·s
10 k
60 Hz. 0.7540 Vrms
2 mV·s
2
2.83 mV·s
8
14
300 µV·s 10 k
1 kHz.
1.257 Vrms 200 µV·s
3
283 µV·s
9
15
30 µV·s
10 k
1 kHz. 0.1257 Vrms 20 µV·s
4
28.3 µV·s
10
16
3 µV·s
10 k
10 kHz. 0.1257 Vrms
2 µV·s
5
n/a
n/a
n/a
AC RMS Calibration
1. Connect Oscillator to Model 480 input terminals (observe ground) using the 1 µF series capacitor
in series with the signal lead.
2. Connect DVM in parallel with the Model 480 input terminals, set to AC.
3. Set Model 480 units to mV·s.
4. Set Model 480 to AC, non-peak operation.
5. Set Model 480 range (per Table 8-1).
6. Set Model 480 input resistance (per Table 8-1).
7. Set Oscillator to the testing amplitude and frequency (per Table 8-1), sine, continuous.
8. Calculate Ideal V·s = Voltmeter reading / 2
f.
9. Wait 30 seconds.
10. Get Actual Model 480 reading.
11. Calculate Calibration Constant = 1e-7
Ideal / Actual.
NOTE:
This value must be 1e-7
11%. A value outside this tolerance indicates a major malfunction
of the Model 480 that requires repair.
Содержание 480
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