Ma Or 0-10 Vdc Bms Reset Signal; Calibration For Bms Configuration - EngA C-TRAC2 Installation, Operation And Maintenance Manual

A
Room Temperature
Room Set Point
Room stat satisfied
Room temp. colder than set-point
Room temp. hotter than set-point

4-20 ma or 0-10 VDC BMS Reset Signal

Discharge air control with the BMS reset signal of 4-20 ma or 0-10 VDC modifying the discharge
temperature. (As the signal strength increases above 12 MA or 5.5 VDC the discharge temperature is driven
warmer; as the BMS signal falls below 12 MA, 5.5 VDC the discharge temperature is driven colder.)
NOTE:
At approximately 5.5 VDC or 12 ma input from the BMS there would be no reset occurring.
As the BMS input voltage deviates from this voltage, the C-TRAC2.1 will reset the
discharge up or down.
NOTE:
If the control is set up for a BMS signal and that signal is not connected, the C-
TRAC will interpret the lack of voltage as a full call for reset downwards. If the
BMS signal is not connected the BMS dipswitch should be off
The BMS signal is wired to the optically isolated "+" and " " terminals.
Pots 9 and 10 relate to BMS reset. As described below, pot 10 is the calibration pot.
Pot 9 determines the amount of authority being given to the BMS reset. Setting "2" allows ±4º and setting
"5" allows as much as ±25ºF on a 0 to 10 VDC system (±20º on a 4 to 20 ma system).

Calibration for BMS Configuration


Set dipswitch 1 "on", and dip switches 2, 3, 4 and 5 "off".

Calibrate the discharge sensor first using the method below.
Approximate relationship between 0-10 VDC and 4-20 ma signal is:
IOM-12
RESET CONTROL
Room Hot
Pivot
Point
Room Cold
Page 13
C-TRAC2.1 MANUAL
Unit controls discharge temperature as per
discharge set point.
Unit controls discharge temperature as per discharge
set point plus selectable amount on pot 5 (room-reset
factor).
Unit controls discharge temperature as per discharge
set point minus selectable amount on pot 5 (room-
reset factor).
Discharge Temperature
Warm Discharge
Manual Discharge Set Point
Cool Discharge
.
March 1999 R1