SIEMENS QBE3000/3100 differential pressure

QBE3100-D series: Only supports DC 11... 33 V power supply, typical power consumption<20 mA. Note: When supplying 4-20 mA circuit, its working resistance (load) needs to meet the formula:

RL≤V supply−11V 0.02  A

RL≤ 0.02AV supply−11V

For example, when the supply voltage is 24 V DC, the maximum load resistance is (24-11)/0.02=650 Ω. If the supply voltage is 18V, the maximum load is 350 Ω. When designing, it is necessary to ensure that the input impedance of the PLC/DCD card is within this range.

4.2 Output signal characteristics

0... 10 V output (QBE3000): Output short-circuit protection and reverse polarity protection. Require the input impedance of the receiving end to be greater than 10 k Ω, otherwise it will cause voltage division errors.

4-20 mA output (QBE3100): Two wire current loop, also equipped with short-circuit and reverse protection. Current output is particularly suitable for long-distance transmission (up to hundreds of meters) and harsh electromagnetic environments on site.

4.3 Dynamic Response

Response time:<5 ms (from pressure step change to output signal reaching 90% final value). This is much faster than conventional mechanical differential pressure switches (usually 100-500 ms) and is very suitable for fast pressure fluctuation monitoring or PID closed-loop control.

Load alternating frequency: Supports up to 50 Hz, which means accurate output can still be achieved with 50 pressure changes per second. The sensor can still faithfully reflect high-frequency pressure components such as compressor pulsation and pump cavitation.

Mechanical installation and process connection

5.1 Pressure interface

The sensor is equipped with G1/8 "external thread as the standard pressure interface. Two adapters are included with the product, specifically designed to connect copper pipes with an outer diameter of 6 mm (commonly used for refrigerant, water pressure, or pneumatic signal pipelines). If other specifications of pipelines (such as 1/4 "NPT or 10mm nylon pipes) need to be connected on site, the adapter should be purchased by oneself.

Please note during installation:

Two pressure interfaces are labeled as "High" (P1) and "Low" (P1) respectively, P2）。 Do not connect in reverse, otherwise the output signal will decrease in reverse as the pressure difference increases (but will not damage the sensor).

Allow unilateral overload (only P1 or P2 side pressurized) to reach twice the nominal range. For example, a sensor with a range of 1 bar can achieve a maximum pressure of 2 bar on one side without damage. But if it exceeds twice the range for a long time, it is still recommended to use a three valve group or a five valve group for protection.

Medium temperature range: -15...+85 ℃. For steam or high-temperature hot water (>85 ℃) applications, condensation bends or heat sinks need to be installed.

5.2 Shell and Protection

Shell material: Aluminum alloy (AlMgSi1), cover made of aluminum; The part in contact with the medium is made of stainless steel 1.4305 (equivalent to 304 stainless steel) and ceramic components.

Protection level: IP65 (IEC 60529). When installed correctly and the cable sealing joint (PG9) is tightened, it can resist water jet and dust intrusion. But it is not suitable to be immersed in water for a long time.

Electrical interface: Comes with a plug that complies with DIN EN 175301-803-A standard (not pre connected), containing a sealing ring and PG9 cable connector. Users need to weld or crimp internal wires themselves. The plug is designed with an anti misoperation structure and allows for 360 ° rotation to adjust the direction of the outgoing line.

5.3 Installation bracket and direction

The sensor comes with a stainless steel (1.4305) mounting bracket that can be fixed to pipes, walls, ceilings, or control cabinets. Any installation direction is acceptable - because factory calibration is performed in the standard direction with the pressure interface facing downwards, but internal temperature compensation and gravity effects have been corrected. To ensure long-term stability, it is recommended to keep the sensor as high as possible above the process pipeline to prevent condensation from flowing back into the ceramic components.

Accuracy and performance data

The following are the common measurement characteristics across the entire series, based on factory calibration (compliant with EN 60770):

Parameter Value Remarks

Comprehensive accuracy (linear+hysteresis+repeatability)<± 0.5% FS FS=full scale

Zero offset<± 0.4% FS can be ignored

Zero temperature coefficient (TC zero)<± 0.04% FS/K Zero drift caused by temperature change per Kelvin

Sensitivity temperature coefficient (TC sensitivity)<± 0.015% FS/K with minimal gain drift

Long term stability ± 0.5% FS 1-year cycle

Resolution 0.1% FS analog output without quantization step

Response time<5 ms electronic response, no mechanical hysteresis

Compatibility, Compliance, and Environmental Product Declaration

7.1 System compatibility

The output signal of QBE3000/QBE3100 is an industrial standard analog quantity, which can be connected to:

Siemens building control products (Desigo, Apogee, Synco)