Monitor And Controller Mac-21; Advantages Compared To Other Test Sets - ETI PI-6000 Instruction Manual

Electrical Test Instruments PI-6000
Section II - Detailed Description
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MONITOR AND CONTROLLER MAC-21

The MAC-21 microprocessor-based measurement and control unit features
digital readout of current and time enhanced by digital signal processing.
Pulse (memory) mode provides fast and accurate automatic evaluation of
output current pulses as short as one-half cycle.
The MAC-21 incorporates a precision A/D converter and special firmware for
true-RMS continuous and pulse current reading with much greater accuracy.
It also utilizes a sophisticated current sensing system for more reliable current
latch mode operation and better timing accuracy. An LED digital readout for
current in four ranges from 1000 A to 100 KA reduces the chance of operator
error.
An integral auto ranging timer with LED readout provides four digits in
seconds or cycles mode, with a resolution of 0.001 second or 0.5 cycle. A preset
function allows you to set a maximum ON time in seconds or cycles, for
convenient "jogging" of output to desired current or setting time for heat runs
and long-time tests.
A current hold feature is also built in. When the desired current is displayed, a
simple touch of the MAINTAIN key activates the function, which automatically
adjusts the motorized rheostat to hold the current within 5 amperes.
The memory current displayed after a test indicates the true RMS value of the
entire pulse, no matter how long or short it was, except for instantaneous trip,
where the peak RMS value is used. After a test, it is possible to read the peak
RMS value, which indicates the amount of DC offset or distortion, or the last
displayed average RMS reading, which is useful for pickup testing.
The metering and control package are designed to be removed and replaced
very easily, so that it may be transported separately.

ADVANTAGES COMPARED TO OTHER TEST SETS

Several changes have been made in the design of high current test sets since
early models such as the EIL BTS-50, many of which are important for safety and
convenience of operation.
The oldest test sets, made by companies such as Multi-Amp and EIL, used large
variable autotransformers and high current step-down transformers to
generate high current output. Tapped autotransformers provided coarse steps
for several ranges of output current, as well as selectable input voltage. These
old test sets used large, heavy iron-core CTs to measure output current with iron
vane analog meters, often with pointer preset mechanisms to read current
pulses. Times were displayed on electromechanical timers, suitable only for long
time measurement.
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