Guildline 7340 Series User manual

TECHNICAL MANUAL
FOR
SERIES 7340
AC CURRENT SHUNTS
NOTICE
The contents and information contained in this manual are proprietary to Guildline
Instruments. They are to be used only as a guide to the operation and maintenance
of the equipment with which this manual was issued and may not be duplicated or
transmitted by any means, either in whole or in part, without the written permission
of Guildline Instruments.
TM7340-B-00
January 20, 2011

7340
TM7340-B-00
January 20, 2011
1
INTRODUCTION
The Guildline model 7340 series of four-terminal AC CURRENT SHUNTS are designed as high
accuracy and stability standards with very low temperature and power coefficients. These shunts are
designed to have extremely small values of reactance up to a frequency of 100 kHz and output voltages
in the range of 0.2 to 1 Volt over specific current ranges from 3 mA to 100 A.
The 7340 AC Current Shunts can be used for a variety of AC/DC current measurement applications and
have nominal impedances in the range of 100 ohms to 0.004 ohms. Applications include the calibration
of precision AC current sources, multi-function calibrators, high accuracy digital multi-meters and
transconductance amplifiers. The current shunts may also be used to provide traceable currents up to
100 A with the utilization of traceable voltages sources from DC to 100 kHz. The lower resistance value
shunts may be used as burdens for current transformers and for AC power and energy measurements.
The very low phase shift of the shunts makes accurate higher frequency power measurements practical.
The output voltage of the shunts faithfully reproduces the current waveform even under highly distorted
current conditions.
The shunts are designed to operate at specific current ranges. Models for currents below 10 A are
specified with natural cooling. Models above 3 A require forced air cooling. Model 73401 Forced Air
Convection Unit is recommended to provide forced air cooling and a stabilized environmental
temperature for the shunts. Resistance values vary depending on specific current ranges from 0.004 ohms
to 100 ohms in a 1, 3, 10 ratio series.
For models with currents of 25 A and lower, a UHF type connector on the back face of the shunt is
provided for connection to the current source to be measured. A BNC connector on the front face is
provided for connection to a voltmeter or other potential measuring device. The enclosure is isolated
from the input and output connector shells and a separate binding post is provided for connection to an
earth ground or a guard potential. For models above 25 A an LC type connector is provided for
connection to the current source.
Figure 1 details mechanical outline. Figure 2 shows schematic detail. Series adapters are available for
connecting the shunts in series with the device to be calibrated. When using the series adapter above 10
kHz it is advisable to make two sets of measurements; one with the normal positioning of the reference
and UUT shunt and a second set of measurements with the shunt position reversed. This will remove the
effect of the parallel capacitance between the two shunts when the average of the two measurements is
calculated.
Maintenance of the shunt consists of routinely inspecting the unit for physical damage and cleanliness.
The screws around the circumference of the enclosure and the connectors should be checked for
tightness periodically. Cleaning with a dry clean cloth is recommended. Water or other solvents should
not be used as this may damage the surface of the shunt panels.

7340
TM7340-B-00
January 20, 2011
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Figure 1: Mechanical Outline

7340
TM7340-B-00
January 20, 2011
3
Figure 2: 73401 Installed on 7340

7340
TM7340-B-00
January 20, 2011
4
OUTPUTINPUT
PCB
x2
THE 7340/x
SHOWING 2 OF 100 OR
MORE ARMS/PATHS OF
SHIELD
ENCLOSURE
Figure 3: Schematic Detail

7340
TM7340-B-00
January 20, 2011
5
SPECIFICATIONS
°
60
18
4.5
6
50
15
4
5.5
45
15
4
5
35
15
3.5
4.5
25
10
3
4
25
10
2.5
3
25
10
2.5
3
25
10
2.5
3
25
10
2.5
3
25
10
2.5
3
º ± º

7340
TM7340-B-00
January 20, 2011
6
GENERAL SPECIFICATIONS
OPTIONS