Section 4: Using the Model 9100: DC Current Function 4.5-11
Final Width = 215mm
4.5.6.5 '50 TURN COIL'
This is the bottom key. DC Current is output, as in 'Normal Output', via the I+ and I-
terminals, with no provision to guard the output.
The facility is intended for use with Option 200: 10- and 50-Turn Current Coils. It is
convenient to use the coils in conjunction with the Lead Kit, Model 9105; but it is possible
to connect the coils directly to the front panel I+ and I- terminals. For the 9100 '50 TURN'
selection, connect the 9100 I- (9105 'LI-' black lead) to the coils 'COM', and the 9100 I+
(9105 'I+ 20A' yellow lead) to the coils '50 TURN'.
The demanded output must be >320mA at the point of selecting the 50-turn coil output
for the 9100 to accept the selection.
If the 9100 output terminals are open-circuited, then a compliance error will be reported.
If the magnitude of the total DCI output from the 50-turn coil (including deviation and
offset) is not greater than 525A, the 9100 will provide a continuous output.
For a total DCI output with magnitude greater than 525A, the length of time that the output
can remain 'ON' is limited by an algorithm:
The total output value is continuously monitored, and the time is counted during
which the output is greater than 525A. The maximum time that the output can remain
on and greater than 525A is 2 minutes, then its value is reduced by half, and a limit
of 525A is imposed. Subsequently, after four times the earlier >525A 'ON' time, the
current can once again be raised above 525A.
Resolution Thresholds
The 9100 firmware will prevent entry to 50-turn coil operation unless the active span in
is either: between -16A and -1000A; or between +16A and +1000A.
The following table shows the spans of output current values against their associated
resolutions, using the 50-turn coil:
Absolute Span of Values
Resolution Negative Positive
100µA -32.0000 A to -16.0010 A +16.0010 A to +32.0000 A
1mA -320.000 A to -016.001 A +016.001 A to +320.000 A
10mA -1000.00 A to -0016.01 A +0016.01 A to +1000.00 A
The same rules governing passage across thresholds and hardware configurations apply
as for the normal output.
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