Trane SCXG-SVX01B-EN manual VAV Box Option, Table O-GI-2. RTM sensor resistance vs. temperature

general

Operation information

must be rated for 12 ma @ 24VDC minimum. This input will override all VOM inputs, if the VOM option is on the unit.

Occupied/Unoccupied Contacts To provide night setback control if a remote panel with night setback was not ordered, install a field-supplied contact. This binary input provides the building’s occupied/unoccupied status to the RTM. It can be initiated by a time clock, or a building automation system control output.The relay’s contacts must be rated for 12 ma @ 24 VDC minimum. Refer to the appropriate wiring diagrams (attached to the unit control panel for the proper connection terminals in the unit control panel.

Emergency Stop Input

A binary input is provided on the RTM board for installation of a field-supplied normally closed (N.C.) switch to use during emergency situations to shut down all unit operations. When open, an immediate shutdown occurs. An emergency stop diagnostic enters the human interface and the unit will require a manual reset. Refer to the unit wiring diagrams (attached to the unit control panel for the proper connection terminals. The switch must be rated for 12 ma @ 24 VDC minimum. This input will override all VOM inputs, if the VOM option is on the unit.

VAV Box Option

To interlockVAV box operation with evaporator fan and heat/cool modes, wire the VAV boxes/air valves toVAV box control connections on the terminal block.

Supply Duct Static Pressure Control The RTM relies on input from the duct pressure transducer when a unit is equipped with IGV or VFD to position the IGV or set the supply fan speed to maintain the supply duct static pressure to within the static pressure setpoint deadband.

RTM Sensors

RTM sensors include: zone sensors with or without setpoint inputs and modes, supply air sensor, duct static pressure, outside air temperature, outside air humidity, airflow proving, and dirty filter.

Table O-GI-2. RTM sensor resistance vs. temperature

temperature, °F	resistance, Ω ohms	temperature, °F	resistance, Ω ohms
-40	346.1	71	11.60
-30	241.7	72	11.31
-20	170.1	73	11.03
-10	121.4	74	10.76
-5	103.0	75	10.50
0	87.56	76	10.25
5	74.65	77	10.00
10	63.8	78	9.76
15	54.66	79	6.53
20	46.94	80	9.30
25	40.40	85	8.25
30	34.85	90	7.33
35	30.18	100	5.82
40	26.22	105	5.21
45	22.85	110	4.66
50	19.96	120	3.76
55	17.47	130	3.05
60	15.33	140	2.50
65	13.49	150	2.05
66	13.15	160	1.69
67	12.82	170	1.40
68	12.50	180	1.17
69	12.19	190	0.985
70	11.89	200	0.830

Table O-GI-3. RTM setpoint analog inputs

cooling or heating setpoint input, °F	cooling setpoint input, °F	resistance, Ω
(using RTM as zone temp. source)	(using RTM as supply air temp. source)
ohms
40	40	1084
45	45	992
50	50	899
55	55	796
60	60	695
65	65	597
70	70	500
75	75	403
80	80	305
NA	85	208
NA	90	111

Table O-GI-4. RTM resistance value vs. system operating mode

resistance	CV units		VAV units
applied to RTM mode
input terminals, ohms	fan mode	system mode	system mode
2320	auto	off	off
4870	auto	cool
7680	auto	auto	auto
10,770	on	off
13,320	on	cool
16,130	on	auto
19,480	auto	heat
27,930	on	heat

Note: Mode boundaries are 1000 to 40,000 ohms. Other boundaries are equal to the midpoint between the nominal mode resistance.

72 SCXG-SVX01B-EN