Specifications

CR3000 Overview
OV1.1 Measurement Inputs
OV1.1.1 Analog Inputs (SE 1-28, DIFF 1-14)
There are 14 differential or 28 single-ended inputs for measuring voltages up
to ±5 V. A thermistor installed in the wiring panel can be used to measure the
reference temperature for thermocouple measurements, and a heavy copper
grounding bar and connectors combine with the case design to reduce
temperature gradients for accurate thermocouple measurements. Resolution on
the most sensitive range is 0.67 µV
OV1.1.2 Signal Grounds (
)
The Signal Grounds (
) should be used as the reference for Single-ended
Analog inputs, Excitation returns, and sensor shield wires.
Signal returns from the CAO and Pulse channels should use the
terminals
located on the CAO and Pulse terminal strip to minimize current flow through
the
grounds on the analog terminal strips.
OV1.1.3 Power Grounds (G)
The Power Grounds (G) should be used as the returns for the 5V, SW12, 12V,
and C1-C8 outputs. Use of the G grounds for these outputs with potentially
large currents will minimize current flow through the analog section, which
can cause Single-ended voltage measurement errors.
OV1.1.4 Ground Lug (
)
The large ground lug is used to tie the ground potential of the datalogger to
earth ground. A conductive connection, using a heavy gage wire, is necessary
to ensure equivalent ground potentials. This path to ground is also used to
shunt incoming electrical transients to ground; these transients may be induced
on the shield wire of the connected sensor leads.
OV1.1.5 Power In (G and 12V)
The G and 12V terminals on the Power In connector plug are for connecting
power from an external battery to the CR3000. These are the only terminals
that can be used to input battery power; the other 12V and SW-12V terminals
are output only.
The green power connector on the wiring panel is a plug in connector that
allows the power supply to be easily disconnected. The power connection is
reverse polarity protected.
For a CR3000 with an alkaline battery base or a rechargeable battery base, it is
not necessary to connect anything to the Power In terminals.
OV1.1.6 Switched 12 Volts (SW-12)
The SW-12 terminals provide an unregulated 12 volts that can be switched on
and off under program control.
OV-3