Dwyer LCR20 - Manual (Page 10)

LCR20 IOM Page 10 of 20 April, 2003
2-8 RTD Input Wiring
Two-wire RTD’s should be used in short lead lengths, if possible, for the
purpose of accuracy. A 0.4 ohm lead resistance of a two-wire RTD will
produce 1 degree C temperature error. RTD connection are shown in
Figure 2-4, with the compensating lead connected to terminal 4. For two-
wire RTD inputs, terminals 2 and 4 should be linked. The three-wire RTD
offers the capability of lead resistance compensation provided that the
three leads are of same gauge and equal length.
2-9 Linear DC Input Wiring
DC linear voltage and linear current connections are also shown in Figure
2-5. Terminal 2 = negative. Terminal 3 = positive.
2-10 Alarm Relay Connections
If your recorder has the optional relay contacts installed, then terminal
blocks J1 and J2 have been provided for connection to the relay on the
microprocessor PC board of the recorder. Refer to Figure 2-4 (page 9) for
the location of J1 and J2 on the microprocessor PC board.
CAUTION! DO NOT TOUCH the terminals of the transformer
while the recorder is connected to the main AC power supply.
To avoid the risk of possible electric shock, unplug or disconnect
the recorder from the main power supply before attempting to
access the terminals of the relay. If the recorder is installed with
the battery back-up option, disconnect the 9 Volt battery to avoid
damaging the recorder and draining the battery.
The recorder has a hinged chart plate held in place by two (2) screws
located on the right hand side of the chart plate. Remove these two
screws and open the hinged chart plate. See Figure 2-5 (pg. 13) for screw
location.
The relay(s) is (are) rated for the following maximum Values:
2.0 AMPS at 25VDC, 1.0 AMP at 120VAC
Warning: Damage to the recorder may result if the ratings for the
relay is exceeded.