ACI A-TT Duct Series Duct Humidity Temperature Transmitter Series Sensor Instruction Manual
- June 13, 2024
- ACI
Table of Contents
ACI A-TT Duct Series Duct Humidity Temperature Transmitter Series Sensor
Instruction Manual
GENERAL INFORMATION
The A/TT Duct Series sensors and transmitters are single point sensors that output 4-20 mA with an optional voltage signal output of 1-5VDC or 2-10VDC signal. The sensor is designed for use with electronic controllers in commercial heating and cooling building management systems. All A/TT temperature transmitters can be powered from either an unregulated or regulated 8.5-32 VDC power supply.
The A/RH Duct Series sensor is a relative humidity transmitter that can be powered with either an AC or DC supply voltage. The RH Duct transmitter is field selectable with a 4-20 mA, 0-5 VDC, or 0-10 VDC output signal that is equivalent to 0 to 100% RH. All RH units are shipped from the factory set to 4-20 mA output.
FIGURE 1: ENCLOSURE DIMENSIONS
For optimal readings, follow these tips:
- The sensor should be mounted in the middle of the duct where air circulation is well mixed (no stratification), and not blocked by obstruction. Stratification and obstructions can cause sensing errors. An example is downstream from a heating or cooling coil.
- Duct probe should be placed (3) to (4) duct segments down from any bend or obstructions and away from 90° bends.
- Mount the sensor on the top or sides of duct work; mounting on the bottom risks damage due to moisture
MOUNTING INSTRUCTIONS
The Nema 4X enclosure (-4X) requires a 1.25” (31.75 mm) hole – see FIGURE 1. After drilling, insert the probe through the hole until the foam pad is tight to the duct. Drill pilot holes for the mounting screws. Use the enclosure as a guide, or use the dimensions listed on the right to measure out. Now fasten and insert mounting screws through the mounting holes and tighten until the unit is held firmly to the duct – see FIGURE 2 (p. 2). Refer to Wiring Instructions (p. 1-4) to make necessary connections.
WIRING INSTRUCTIONS
PRECAUTIONS
- RH Transmitter can be powered by VAC or VDC.
- Temperature transmitter is powered by 24 VDC only.
- Remove power before wiring. Never connect or disconnect wiring with power applied.
- When using a shielded cable, ground the shield only at the controller end. Grounding both ends can cause a ground loop.
FIGURE 2: MOUNTING DIMENSIONS
FIGURE 3: PRINTED CIRCUIT BOARDS
PRECAUTIONS (Continued)
- It is recommended you use an isolated UL-listed class 2 transformer when powering the unit with 24 VAC. Failure to wire the devices with the correct polarity when sharing transformers may result in damage to any device powered by the shared transformer.
- If the 24 VDC or 24 VAC power is shared with devices that have coils such as relays, solenoids, or other inductors, each coil must have an MOV, DC/AC Transorb, Transient Voltage Suppressor (ACI Part: 142583), or diode placed across the coil or inductor. The cathode, or banded side of the DC Transorb or diode, connects to the positive side of the power supply.
TEMPERATURE
Open the cover of the enclosure. The temperature transmitter is located on the
inside of the cover. ACI recommends 16 to 26 AWG twisted pair wires or
shielded cable for all transmitters.
Twisted pair may be used for 2-wire current output transmitters or 3-wire for voltage output. Refer to FIGURE 5 (p. 3) for wiring diagrams. All wiring must comply with local and
National Electric Codes. All ACI TT and TTM temperature transmitters can be powered from either an unregulated or regulated 8.5 to 32VDC power supply
FIGURE 4: SHARED POWER CONNECTIONS and ANALOG OUTPUTS
VOLTAGE OUTPUTS
CURRENT OUTPUTS
WIRING INSTRUCTIONS (Continued)
TEMPERATURE (Continued)
The TT and TTM DO NOT support an AC input. All TT and TTM temperature
transmitters are reverse polarity protected. After wiring, attach the cover to
the enclosure.
The minimum voltage at the transmitter power terminal is 8.5V after load resistor voltage drop.
- 249 Ω load resistor (1-5 VDC output) = 13.5 V min supply voltage
- 499 Ω load resistor (2-10 VDC output) = 18.5 V min supply voltage
Note: All RTD’s are supplied with (2) or (3) ying lead wires. ACI’s transmitters are supplied with a 2 pole terminal block for RTD sensor connections. When wiring a 3 wire RTD, connect the (2) common wires (same color) together into the same terminal block.
TEMPERATURE – MULTIPLE CONNECTIONS
Several transmitters may be powered from the same supply as shown in FIGURE 6
(bottom). Each transmitter draws 25mA; refer to the following equation to
obtain the number of permissible transmitters: [# Transmitters] = [Current] /
(25 mA).
Example:
- If [Current] = 1.5 A, then…
- [# Transmitters] = 1.5 A / 25 mA
- [# Transmitters] = 60
Therefore a 1.5 A power supply will safely power up to 60 transmitters.
FIGURE 5: TEMPERATURE WIRING
STANDARD UNITS
VOLTAGE OUTPUT (1-5 or 2-10 VDC)
POTTED UNITS
CURRENT OUTPUT (4 to 20 mA)
VOLTAGE OUTPUT (1-5 or 2-10 VDC)
FIGURE 6: MULTIPLE TRANSMITTER CONNECTIONS
RELATIVE HUMIDITY WIRING INSTRUCTIONS
The RH transmitter is located on the bottom of the enclosure. ACI recommends
16 to 26 AWG twisted pair wires or shielded cable for all transmitters.
Twisted pair may be used for 2-wire current output transmitters or 3-wire for
voltage output. Refer to FIGURE 7 (top) for wiring diagrams.
RH OUTPUT SIGNALS
Switches 6, 7, and 8 are used to set the RH output signal. Refer to FIGURE 8
(bottom) for switch settings.
HUMIDITY REVERSE ACTING OUTPUT
The output is direct acting and can be changed to reverse acting mode. The
output range stays the same but the corresponding RH value is opposite
Example:
Direct Acting (DA)
- 0-10 V output mode,
- 0 V = 0% RH and 10 V = 100% RH
Reverse Acting (RA)
- 0-10 V output mode,
- 0 V = 100% and 10 V = 0%
To change the transmitter to reverse acting or back to direct acting, set switch 4 to ON to put the unit in setup mode. After switch 4 is on, turning switch 2 to ON will put the unit in direct/reverse acting mode. When switch 2 is set to ON, the output can be used to show if the unit is in direct or reverse acting mode. For direct acting, the output will be 1 V for 0-5 V, 2 V for 0-10 V, and 7.2 mA for 4-20 mA. For reverse acting the output will be 4 V for 0-5 V, 8 V for 0-10 V, and 16.8 mA for 4-20 mA.
With switches 2 and 4 ON, each time switch 5 is set to ON the output will change to reverse acting or direct acting. To reset the unit to the default setting, toggle both switches 5 and 6 ON then OFF while both switches 2 and 4 are ON. When all calibration is completed, remember to place the switches back into the positions that correspond to the output needed as shown in FIGURE 8 (bottom).
RH CALIBRATION INSTRUCTIONS
Note: This is only a single point calibration. All transmitters are factory calibrated to meet/exceed published specifications. Field adjustment should not be necessary.
FIGURE 7: RH OUTPUT SIGNALS
FIGURE 8: RH OUTPUT SWITCHES
RH CALIBRATION INSTRUCTIONS (Continued)
The dipswitch allows the user to calibrate the sensor through the software.
Setting switch 4 ON will put the transmitter into setup mode allowing the
increment and decrement to work. Once in setup mode, the output will change to
50% (2.5 V for 0-5 V, 5 V for 0-10 V, 12 mA for 4-20 mA). Each increment or
decrement step will cause the output to change by 0.1 V for 0-5 V, 0.2 V for
0-10 V, and 0.32 mA for 4-20 mA in setup mode. This can be used to show the
user how far offset the transmitter is. To see the starting point again set
switch 1 ON. This will show the 50% output again. When the unit is out of
setup mode the output will go back to RH output. The maximum offset is 10%.
There can be a total of 20 increments.
Increment RH Output
This will shift the RH output linearly up in 0.5% steps. Switch 4 must be set
to ON first. After switch 4 is on, each time switch 5 is set ON the RH output
will increase by 0.5%. The increase goes into effect each time switch 5 is set
to ON.
Decrement RH Output
This will shift the RH output linearly down in 0.5% steps. Switch 4 must be
set to ON first. After switch 4 is on, each time switch 6 is set ON the RH
output will decrease by 0.5%. The decrease goes into effect each time switch 6
is set to ON.
Reset RH Output
This will reset the RH output back to the original calibration. Switch 4 must
be set to ON first. After switch 4 is on, toggle switches 5 and 6 ON then OFF.
After 5 and 6 are OFF, slide switch 4 OFF. When all calibration is completed,
remember to place the switches back into the positions that correspond to the
output needed as shown in FIGURE 8 (p. 4).
RH TEST INSTRUCTIONS
Test mode will make the transmitter output a fixed 0%, 50%, or 100% value. The
sensor will not affect the transmitter output. This is used for
troubleshooting or testing only.
Switches 1, 2, and 3 are used for test mode. The output will be a fixed 0%, 50%, or 100% signal that corresponds to the output selected with switches 6, 7, and 8. Refer to FIGURE 9 (right) for switch settings
FIGURE 9: RH SELECTION SWITCHES
RH CONVERSION FORMULAS
| 4-20 mA| 0-5 VDC| 0-10 VDC
---|---|---|---
Formula:| ([mA signal] -4) / 0.16 = percent RH| [VDC signal] / 0.05 =
percent RH| [VDC signal] / 0.10 = percent RH
Example:| 12 mA output signal(12 – 4) / 0.16 = 50% RH| 1.25 vdc output
signal1.25 / 0.05 = 25% RH| 7.50 vdc output signal7.50 / 0.10 = 75% RH
WARRANTY
The ACI Room Series RH sensors are covered by ACI’s Five (5) Year Limited
Warranty, which is located in the front of ACI’S SENSORS & TRANSMITTERS
CATALOG or can be found on ACI’s website: www.workaci.com.
W.E.E.E. DIRECTIVE
At the end of their useful life the packaging and product should be disposed
of via a suitable recycling centre. Do not dispose of with household waste. Do
not burn.
TROUBLESHOOTING
HUMIDITY READING PROBLEM
No Reading
- Check that you have the correct supply voltage at the power terminal blocks.
- Check that wiring configurations and all DIP switch settings are as in FIGURE 7 and 8.
- Verify that the terminal screws are all connected tightly and that all of the wires are firmly in place.
Erratic readings
- Verify that all of the wires are terminated properly.
- Make sure that there is no condensation on the board.
- Check that the input power is clean. In areas of high RF interference or noise, shielded cable may be necessary to stabilize signal.
Inaccurate readings
-
Verify proper mounting location to conrm no external factors (see mounting locations above).
-
Check the output (voltage or current) against a highly accurate recently calibrated secondary reference. Measue RH at the location of the sensor using the secondary reference, then calculate the RH percentage using the RH CONVERSION
FORMULAS (p. 5). Compare the calculated output to reference. -
If the sensor is brand new, leave the sensor powered for at least 30 minutes to stabilize.
-
If you suspect that the transmitter is not reading within the specied tolerance, please contact ACI for further assistance
TEMPERATURE PROBLEM
No Reading
- No power to board – check voltage at power terminal – should be between +8.5 and 32 VDC.
Reading too Low
- RTD wires shorted. Disconnect wies from terminal block and check with ohmmeter. Reading should be close to 100 Ω or 1 KΩ.
- RTD Improper range of transmitter (too low). Check current or voltage – should be between 4-20 mA, 1-5 V, or 2-10 V.
Reading too High
- RTD opened. Disconnect sensor wires from terminal block and check with ohmmeter. Reading should be close to 100 Ω or 1 KΩ.
- Improper range of transmitter (too high). Check current or voltage – should be between 4-20 mA, 1-5 V, or 2 10 V.
Reading is Inaccurate
- Sensor check: Disconnect sensor wires from terminal block and check with ohmmeter. Compare the resistance reading to the Temperature vs Resistance curves located on ACI’s website.
- Transmitter check: Make sure sensor wires are connected to terminal block. Determine that the proper output is being transmitted based on predetermined span:
- Go to ACI Website, Span to Output Page: http://www.workaci.com/content/span-output
- Enter the low end of the span
- Enter the high end of the span
- Click on the output of the transmitter. This will generate a span to output chart.
- Measure output of transmitter.
- Compare measured output to calculated output
PRODUCT SPECIFICATIONS
SENSOR NON-SPECIFIC
Enclosure Specifications (Material, Temperature, NEMA/IP
Rating):| “-4X” Enclosure: Polystyrene Plastic; UL94-V2; -40 to
158°F (-40 to 70°C); NEMA 4X(IP 66)
Tube Material:| Slotted PVC without filter
RH TRANSMITTER
RH Supply Voltage (Reverse Polarity Protected):|
4-20 mA: 250 Ω Load: 15 – 40 VDC / 18 – 28 VAC | 500 Ω Load:
18 – 40 VDC / 18 – 28 VAC 0-5 VDC: 12 – 40 VDC / 18 – 28 VAC | 0-10
VDC: 18 – 40 VDC / 18 – 28 VAC
RH Supply Current (VA):| Voltage Output: 8 mA
maximum (0.32 VA) | Current Output: 24 mA maximum (0.83 VA)
RH Output Load Resistance:| 4-20 mA: 700 Ω maximum |
0-5 VDC or 0-10 VDC: 4 KΩ Minimum
RH Output Signal:| 2-wire: 4 – 20 mA (Default) | 3-wire:
0-5 or 0-10 VDC & 4 – 20 mA (Field Selectable)
RH Accuracy @ 77°F (25°C):| +/- 1% over 20% RH Range
between 20 to 90% | +/- 2%, 3%, or 5% from 10 to 95%
RH Measurement Range:| 0-100%
Operating RH Range:| 0 to 95% RH, non-condensing (Conformally
Coated PCB’s)
Operating Temperature Range:| -40 to 140 °F (-40 to 60 °C)
Storage Temperature Range:| -40 to 149 °F (-40 to 65 °C)
RH Stability | Repeatability | Sensitivity:| Less
than 2% drift / 5 years | 0.5% RH | 0.1% RH
RH Response Time (T63):| 20 Seconds Typical
RH Sensor Type:| Capacitive with Hydrophobic Filter
RH Transmitter Stabilization Time:| 30 Minutes (Recommended
time before doing accuracy verification)
RH Connections | Wire Size:| Screw Terminal Blocks (Polarity
Sensitive) | 16 (1.31 mm²) to 26 AWG (0.129 mm²)
RH Terminal Block Torque Rating:| 4.43 to 5.31 lb-in
(0.5 to 0.6 Nm)
RH NIST Test Points:| Default Test Points: 3 Points
(20%, 50% & 80%) or 5 Points (20%, 35%, 50%, 65% & 80%) 1% NIST
Test Points: 5 Points within selected 20% Range (ie. 30%-50% are 30,
35, 40, 45 & 50)
TEMPERATURE TRANSMITTER
TT Supply Voltage:| +8.5 to 32 VDC (Reverse Polarity Protected)
Supply Current:| 25 mA minimum; 250 Ω Load: +13.5 to 32
VDC | 500 Ω Load: +18.5 to 32 VDC
TT Maximum Load Resistance:| (Terminal Voltage – 8.5 V) |
0.020 A
TT Output Signals:| 2-Wire: 4-20 mA Current Output |
3-Wire: 1-5 VDC/2-10 VDC Voltage Output
TT Calibrated Accuracy | Linearity ¹:| T.
Spans < 500 °F (260 °C): +/- 0.2% | T. Spans
> 500 °F (260 °C): +/- 0.5%
TT Temperature Drift ²:| T. Spans < 100
°F (38 °C): +/- 0.04%/°F | T. Spans > 100 °F
(38 °C): +/- 0.02%/°F
TTM100/TTM1K Certification Points:| 3 Point NIST:
20, 50, 80% of span | 5 Point NIST: 20, 35, 50, 65, & 80% of span
TT Warm Up Time:| 10 Minutes | +/- 0.1%
Warm Up Drift:| -40 to 185 °F (-40 to 85 °C)
Transmitter Operating Temperature/RH Range:| 0 to 90% RH,
non-condensing
Platinum RTD (PTC) Number Wires | Wire
Colors:| Two | TT100 & TTM100: Brown/Brown | TT1K & TTM1K:
Black/Black
Platinum RTD Sensor Output @ 32°F (0°C):|
A/TT100/TTM100 Series: 100 Ω | A/TT1K/TTM1K Series: 1000 Ω
Platinum RTD Tolerance Class | Accuracy:| +/- 0.06%
Class A | Tolerance Formula: +/- °C = (0.15 °C + (0.002 * |t|),where
|t| is the absolute value of Temperature above or below 0°C in °C)
Platinum RTD Sensor Stability:| +/-0.03% after 1000 Hours @
572 °F (300 °C)
Platinum RTD Response Time (63% Step Change):| 8
Seconds nominal
Automation Components, Inc.
2305 Pleasant View Road | Middleton, WI 53562
Phone: 1-888-967-5224 | Website:
workaci.com
Automation Components, Inc.
2305 Pleasant View Road
Middleton, WI 53562
Phone: 1-888-967-5224
Website: workaci.com
References
- Building Automation Sensors | Automation Components, Inc.
- Building Automation Sensors | Automation Components, Inc.
- Span To Output | Automation Components, Inc.