Trane RTWA 70-125 TON - Manual (Page 50)

50 RLC-SVD03A-EN
Module Power and Miscellaneous I/O
Options Module (CSR) (1U2)
ƽ WARNING
Live Electrical Components!
During installation, testing, servicing and troubleshooting of this
product, it may be necessary to work with live electrical
components. Have a qualified licensed electrician or other
individual who has been properly trained in handling live
electrical components perform these tasks. Failure to follow all
electrical safety precautions when exposed to live electrical
components could result in death or serious injury.
Test Points
There are three test points associated with the CSR module. They are easily
read with a DC voltmeter by probing the PC board solder pads found in the
upper left hand corner of the module. The positive meter lead should be
connected to the pad, while referencing the negative meter lead to the board
edge ground plane.
Note: don't use the aluminum module enclosure as a reference as it has
an anodized surface with insulating properties. The DC voltages shall be
within the tolerance specified below. If not replace the module.
TP1: + 5 volts DC ±5%
TP2: + 6 volts DC ±5%
TP3: +12 volts DC ±25%
Switch SW-1
Switch SW1 is used to configure the External Chilled Water Setpoint input
and the External Current Limit Setpoint input for either a 2-10VDC, or a 4-
20ma signal. With the respective switch closed (on), a shunt resistor is
switched into the input circuit to provide a fixed low value input impedance
(499 ohms) for current loop operation. With the switch off, the input
impedance is differentially 40Kohms.
External Setpoint Inputs (4-20ma/2-10VDC)
The chiller setpoint source should always be set to LOCAL when using any
external inputs, except a Tracer. When using a Tracer, always set the chiller
setpoint source to the Tracer mode. The setpoint source can be found in the
Operator Settings Menu.
These inputs accept either an isolated 4-20mA or 2-10VDC signal from an
external controller or programming resistor connected to an internal +5V
source. The switches SW1-1 and SW1-2 are used to select either the voltage
or current option for External Chilled Water Setpoint and External Current
Setpoint respectively. See Test Points, above. Alternately, either input may be
used with a resistor or potentiometer.
NOTE: Note: For proper operation, the 4-20mA/2-10VDC inputs are required
to be used with a current or voltage source that:
1. Is isolated (floats) with respect to ground, or