Fluke 52120A, User Manual

Page: 40 / 98

52120A
Operators Manual
2-8
Load Regulation
As with all current sources, the Product has finite output impedance and thus suffers from
frequency dependent load regulation errors when in Open Loop mode. The effects of
worst case load regulation are included in the Product specification as a percentage of full
range. For low impedance loads the load regulation effects are very small and the percent
of full range specification adder is pessimistic. A40B shunts are a good example of low
impedance loads. The absolute transconductance accuracy performance of the Product is
significantly better than specification into such devices if you keep inductive loop
impedance to a minimum in long cables.
When you connect the Product to a load, keep the cable length to a practical minimum.
Also keep the cables close together to keep loop impedance low. The high current
connection cables that shipped with the Product add around 2
μ
H to the load impedance
if tied together at 150 mm (6 inch) intervals.
For best accuracy, use ac-dc comparison when you calibrate shunts. In this type of
measurement, the ac current is compared to a known dc current. Accuracy is supplied by
an ac-dc reference instrument such as a thermal voltage convertor. The Fluke 792A or a
Fluke 5790A for example. To use this type of measurement, refer to the documentation
that comes with the ac-dc reference standard.
The short-link cable that comes with the Product is used when a short loop between the
high current HI and LO terminals is necessary. The short loop connector has very low
inductance. The low inductance means you can do clamp meter performance tests at
higher frequencies than is possible with longer, more inductive cable configurations.
Product Operation Behavior
The Product has internal detectors for Product protection. Equipment connected to the
Product receives protection as well. When the Product senses an unexpected condition,
the Product goes in to standby (STBY) mode. An interruption of mains power input for
three milliseconds or more causes the Product to go to its power up state with the output
off. This makes sure the circuits are in a safe condition while internal power supplies are
available.
When the Product is in operate (OPR) mode, a change of state such as an error or key
push causes the Product to go to standby (STBY) mode.
Front-Panel Indicator Colors
Many of the front-panel keys have indicators embedded in them. The color and condition
of these indicators show different conditions. Table 2-3 is a list of the colors used on the
front-panel keys.
Table 2-3. Front-Panel Indications
Indicator Color/Condition Description
Green
Key function is on. When Operate is on, the indicators in the
OPR key and the set terminals key show green.
Flashing Green
Shows an incompatible condition has been set. Key(s) that flash
green are suggested alternate(s).
Red
Shows an Over Compliance, Over Temperature, or Input Over
Range error.
Amber
Product is in standby mode. The STBY key and the set terminals
key shows amber in standby mode.
Amber (Error condition)
Over Compliance, Over Temperature, or Input Over Range. A
Product in the Master/Slave chain reports an error.