Fluke 540B - High Frequency Voltage Measurement and Calibration

540B
TH ER MA L TRAN SFER STAND ARD
A54
B SH
UNT
•o
CABLE
6002-212860
CURRENT T RA N SFER S WIT CH
o. A40 CURRE NT SHU NT AND CONNECTIONS
THE
RMA L T RAN SFER STANDAR D
A54
SHUN T
A
40A SHUN T
CABLE 6002-212852
b. A40 A CUR R ENT SHUNT AND CONNECTIONS
Figu re 2-8. CABLES AND CONNECTIONS FOR CURRENT SHUN TS
2 -32. HI GH FREQU ENCY VOL TAGE
MEA SUR EM EN T AND CALIBRA TI O N
2-33. GENERAL
2-34. A special cable, supplied with the Model 540B,
provides a means of connecting the output of an external
thermal converter to the HIGH FREQ CONVERTER jack
on the front panel of the Model 540B for high frequency
ac voltage measurements. The Fluke Model A55 Ther-
mal Co nv erter series of nine high frequency thermal
converters are supplied in ranges identica l with the
Model 540B ranges up to and including 50 volts. These
conve rters make accurate measurements up to 50 MHz
possible. When using external thermal converters the
internal t hermocouple, range switch, transfer switch,
search and protection circuits are not used. Since no
protection is provided for the external thermal converter
it will be necessary to use all normal cautions to avoid
overloads. The i
nstruction manual f or the A55 Thermal
Converters should be used to obtain the correction factor
due to transmission line effect s.
CA UTION!
Always use a thermal converter whose r ated
val ue is equal to or greater t han the rms
value of the ac voltage to be measured. If
the approximate value of the ac voltage is
unkno w n, mea sure with a high frequency
voltmeter b efore connecting to the t hermal
co nvert er.
2-35 . MEASURING AN UNKNOWN HIGH FREQUENCY
VOLTAGE
2-36. Comple te the Battery Check of Figure 2-4. Re-
move th e pl ug fr om the HIGH FREQ CONVERTER jack
on th e Model 540B. Connect the se l ec t ed Model A55
Thermal Converter output to th e HIGH FREQ CO N-
VERTER jack u sing the interconnecting cable, sup pli ed
2- 10
with the Model 540B. This cable allows the external
converter to be connected close to the ac being meas -
ured, thus reducing transmission line effects. Connect
the thermal converter to the ac source to be measured.
The voltage may be 1/2 to 1 times the rated value of the
converter. Use the procedure in Figure 2-11.
Note!
Depending on how the Model A55 Thermal
Convert er is co nnected to the source of the
unknown vo ltag e, it may be necessary to
make correct ions for standing waves at
frequencie s above 5 MHz. See the Model
A55 Th e rmal Converter manual for further
information.
2-37. CALIBRATING A
HIGH FREQUENCY VOLTAGE
SOURCE
2-38.
Complete the Battery Check of F igure 2-4. Re-
move the plug f rom the H IGH FREQ CONVERTER jack
on the Model 540B front panel. Connect the selected
Model A55 Thermal Converter output to the HIG .H FREQ
CONVERTER jack u sing the interconnecting cable, sup-
plied with t he Model 540B. This cable allows the ex-
t ernal converter to be connected close to the ac being
calibra t ed, thus reducing tra nsmissio n line effects .
Conn
ec t the thermal converter to the ac source to be
calibrated. The voltage may be 1/2 to 1 times the rated
v alue of the converter. Use th e procedure in Figure
2-12.
Note!
If the input impedan ce of the instrument
being calibrated is not 50 ohms , it may be
necessary to corre ct for the standing wave
between th e center of the tee and the instru-
ment being calibrated at frequenc i es above
5 MHz. See
the Model A55 Thermal Con-
v er t er m anual for further information.