External Current Limit Setpoint (Cls) - Trane RTAA-70 Installation & Maintenance Manual

RTAA-SVX01A-EN
Installation — Electrical

External Current Limit Setpoint (CLS)

This option allows the external setting of the Current Limit Setpoint,
independent of the Front Panel Current Limit Setpoint, by one of three
means:
1. A remote resistor/potentiometer input (fixed or adjustable).
2. An isolated voltage input 2-10 VDC.
3. An isolated current loop input 4-20 mA.
To enable external Current Limit Setpoint operation, "External Current Limit
Setpoint" (Operator Settings Menu), should be set to "E" using the Clear
Language Display.
1. Remote Resistor/Potentiometer Input.
To cover the entire range of Current Limit Setpoints (40 to 120%), a field
furnished 50 Kohm log taper potentiometer (±10%) and a fixed 820 ohm
(±10%) 1/4 Watt resistor should be wired in series and connected to
terminals TB1-6 and TB1-8 of options module 1U2, as shown in
If the potentiometer is to be remotely mounted, it and the resistor must be
connected to the UCM prior to mounting. Then, with the Clear Language
Display showing "Active Current Limit Setpoint" (Chiller Report Menu), the
Clear Language Display can be used to calibrate the positions of the potentio-
meter to correspond with the desired settings for the current limits. External
resistor input values for various current limit setpoints are shown in
Figure 28 Resistor and Potentiometer Arrangement for External Current
Limit Setpoint
Figure 28.
Table 15.
59