Temperature is generally sensed at the tip of the probe. To get an accurate tem
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perature measurement the probe sheath should be well immersed, with ade
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quate depth and fit, into the medium to be measured.
CAUTION: Probes are fragile devices that can be easily damaged by me
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chanical shock, overheating, and absorption of moisture or fluids in the
wires or hub. Damage may not be visibly apparent but nevertheless can
cause drift, instability, and loss of accuracy. Observe the following pre
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cautions:
Do not allow probes to be dropped, struck, bent, or stressed.
Do not overheat probes beyond their recommended temperature range.
Do not allow any part of the probe other than the sheath to be immersed in
fluid.
Do not allow the probe hub or wires to be exposed to excessive temperatures.
Keep the probe wires clean and away from fluids.
6.6 INFO-CON Connector
The probe connects to the top of the 1521 using a Hart INFO-CON connector
(see Figure 3 on page 17). The probe connector will fit snugly and lock into
place when it is fully inserted. The connector includes a memory device that
stores the unique characteristics of the probe, allowing the instrument to mea-
sure temperature accurately. Generally, the probe will be purchased with the
connector attached and programmed by the factory. Connectors can be pur-
chased separately and installed onto probes by the user. The INFO-CON can be
programmed directly from the 1521 by authorized personnel.
If it is necessary to install the INFO-CON onto a probe in the field follow the
diagram below for connecting the wires of the probe to the connector terminals.
Before opening the INFO-CON case, be sure to be grounded with an ESD strap
to avoid damaging the memory chip. For four-wire probes, one pair of wires at
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taches to terminals C1 and P1 and the other pair attaches to terminals C2 and
P2. (C1 and C2 source current and P1 and P2 sense the potential.) If a shield
wire is present it should be connected to the GND terminal (see Figure 6).
A three-wire or two-wire probe can also be used with the 1521. A three-wire
probe is connected by attaching the common wires to the C1 and P1 terminals
and the other wire to the C2 and P2 terminals. The two-wire probe is connected
by one wire to the C1 and P1 terminals and the other wire to C2 and P2. Again,
any shield wire should be connected to the GND terminal (see Figure 6). Rec
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23
6 General Operation
INFO-CON Connector
