SIEMENS QFM31xx series air duct sensor

Range configuration: According to on-site requirements, set the temperature range and display unit through jumper wires;

Power on verification: Connect the power supply and check if the output signal (humidity 0-10V/4-20mA, temperature corresponding range signal) is normal. For models with LCD, it is necessary to confirm the alternating display of temperature and humidity (5-second interval).

Fault diagnosis and spare parts

1. Fault diagnosis (output characteristics when sensor failure occurs)

Fault type: Humidity signal output (U1/I1) Temperature signal output (U2/I2) Remarks

Temperature sensor fault rises to 10V (0-10V output) or corresponding 20mA (4-20mA output) drops to 0V (0-10V output) or corresponding 4mA (4-20mA output). The fault is immediately triggered

The humidity sensor malfunctions for 60 seconds and then rises to 10V/20mA to maintain normal output with a delay of 60 seconds, making it easier for the system to identify

2. Spare parts list (for replacement)

Spare part model, spare part name, and purpose

The AQF3101 filter cap protects the sensing elements inside the probe, preventing dust from entering

Replace damaged temperature and humidity sensing components with AQF3150 sensing head

74 662 01040 1/2 inch rigid conduit adapter for connecting conduit to sensor base

Compliance and physical specifications

1. Certification and Standards

Compliance Directive: Complies with EMC Directive 2004/108/EC (Electromagnetic Compatibility) and AS/NZS 3548 (Radio Interference Emission Framework Standard);

Electrical specifications: The power supply requires the use of a Class II transformer (independent winding, 100% duty cycle), and the selection should consider sensor power consumption and local electrical regulations.

2. Physical specifications

Project specification parameters

Material base/probe: polycarbonate (RAL 7001); Cover plate: polycarbonate (RAL 7035); Flange: PA66 (black)

Protection level IP65 (NEMA 4)

Weight (including packaging) without LCD display: 7.34 ounces (0.208kg); With LCD display: 23.49 ounces (0.666kg)

The wiring terminal is compatible with 14 AWG (1 way) or 16 AWG (2 ways) wires

Engineering precautions

Power selection: Class II transformers must be used with independent winding design to ensure safe isolation;

Cable selection: Shielded twisted pair cables are required for EMC interference environments, and secondary power lines and signal lines need to be twisted to reduce interference;

Wiring specifications: Avoid long-distance parallel laying of cables (too small spacing can easily cause interference), strictly follow the allowed cable length (distinguished by wire diameter);

Maintenance requirements: Regularly check the cleanliness of the filter cap (contamination can affect response speed), and replace it promptly if it is damaged.