The NCS-PT105IISH is a smart pressure transmitter from Microcyber’s NCS-PT105II series. Built on the proven 3151 capacitive pressure sensor platform and powered by 16-bit microprocessor technology, this vertical diffused silicon transmitter supports HART 7 protocol (backward compatible with HART 5/6), delivering simultaneous 4–20 mA analog output and full digital multivariable communication over the same 2-wire loop.
Developed by Microcyber — a national high-tech enterprise affiliated with the Shenyang Institute of Automation, Chinese Academy of Sciences — the NCS-PT105IISH represents a mature, field-proven solution for industrial pressure measurement in oil & gas, petrochemical, power generation, and water treatment industries.
What Is the NCS-PT105IISH?
The NCS-PT105IISH is a vertical diffused silicon HART pressure transmitter that converts process pressure into a standardized 4–20 mA current signal with superimposed HART digital communication. Unlike simple analog transmitters, it can simultaneously transmit up to four process variables (PV, SV, TV, QV) digitally without disturbing the existing 4–20 mA control loop.
NCS-PT105II Series Variants
The NCS-PT105II series is available in multiple sensor technologies to match different application requirements:
- Diffused Silicon (NCS-PT105IIS series): Standard industrial pressure measurement with HART, FF H1, or PROFIBUS PA.
- Monocrystalline Silicon (NCS-PT105IISM series): High-precision applications with superior long-term stability.
- Clamp-On (NCS-PT105IIM series): Non-invasive pressure measurement for hygiene-critical or corrosive processes.
Working Principle: 3151 Capacitive Sensor Technology
Differential Capacitance Sensor Architecture
At the core of every NCS-PT105IISH is a 3151 differential capacitive pressure sensor. The sensor consists of a central measurement membrane serving as one shared electrode, with two fixed electrodes on either side forming two capacitors: CH (high-pressure side) and CL (low-pressure side).
When pressures on both sides are equal, the membrane sits in the center. When high-pressure side exceeds the low-pressure side, the membrane moves toward the low-pressure side, decreasing CH and increasing CL. The key advantage is its linear output, following the ratio:
(CH − CL) / (CH + CL) ∝ ΔP
Signal Processing Chain
- The instrument board converts capacitance changes into digital counts.
- Real-time temperature is acquired for precise thermal compensation.
- The communication board computes final pressure using calibration parameters.
- The HART interface modulates the digital signal using FSK at 1.2 kHz / 2.2 kHz.
Key Features and Specifications
Measurement Performance
| Parameter | Specification |
|---|---|
| Accuracy | ±0.075% of URL |
| Stability | ±0.1% of URL per year |
| Update Rate | 0.2 seconds (HART polling mode) |
| Damping | 0–32 seconds (configurable) |
Signal Output and Communication
| Parameter | Specification |
|---|---|
| Analog Output | 4–20 mA (linear or square root) |
| HART Protocol | HART 7 (backward compatible with 5/6) |
| Loop Voltage | 12.5–45 V DC |
| Electrical Isolation | 500 V AC between input and output |
Explosion Protection — NEPSI Certified
| Certification Parameter | Value |
|---|---|
| Explosion Mark | Ex ia IIC T4 Ga |
| Maximum Input Voltage (Ui) | 30 V DC |
| Maximum Input Current (Ii) | 100 mA |
| Maximum Input Power (Pi) | 0.8 W |
Local Configuration Without a HART Communicator
The NCS-PT105IISH supports fully local configuration via magnetic sticks. Two labeled holes on the transmitter housing — ZERO and SPAN — simulate virtual pushbuttons (Mode, Up, Down, Enter).
Calibration Procedures
- Zero Point Calibration (Mode 08): Apply known zero pressure, set Mode 08, and press Enter until “OK” appears.
- Span Calibration (Mode 09): Apply full-scale pressure, set Mode 09, adjust value using Up/Down, and press Enter to confirm.
Note: Ensure the write-protection jumper is removed before attempting configuration.
Installation Best Practices
Pressure Piping by Medium
- Liquid: Install transmitter below the tap to allow gases to vent into the pipe.
- Steam: Install below the tap; fill impulse piping with water to prevent direct steam contact with the sensor.
- Gas: Install above the tap to allow condensate to drain back into the pipe.
FAQ
What is the minimum loop resistance for HART?
The HART physical layer requires a minimum of 230 Ω. For reliable communication, a 250 Ω resistor is the standard recommendation.
Can the LCD display be rotated?
Yes. The LCD board features a four-position rotation mechanism, allowing you to maintain an optimal viewing angle in vertical or horizontal mounting positions.
How does SIL2 certification benefit safety?
Models like the NCS-PT105IISH are designed for high-reliability environments, reducing the probability of failure on demand (PFD) in Safety Instrumented Systems.
Summary
The NCS-PT105IISH combines 3151 capacitive accuracy, HART 7 multivariable diagnostics, and IP67 ruggedness. It is an ideal solution for modernizing industrial pressure loops while maintaining backward compatibility with existing 4–20 mA infrastructure.