The GSI127 is a high-performance Galvanic Separation Unit from Meggitt's vibro-meter product line. The specific model 244-127-000-017-A1-B01 represents a configuration that integrates multiple advanced features designed for harsh industrial environments. The core mission of this unit is to provide stable, isolated power and signal transmission paths for sensors (such as vibration, pressure) and their signal conditioners. It is a key component in building reliable and safe industrial condition monitoring and predictive maintenance systems.
In complex industrial settings, especially in sectors like energy (power generation), oil & gas, and heavy machinery, measurement systems often face challenges such as high voltage, ground loops, electromagnetic noise, and potentially explosive atmospheres. The GSI127 Galvanic Separation Unit effectively addresses these issues through its exceptional galvanic isolation capability, strong noise immunity, and comprehensive international explosion-proof certifications, ensuring signal integrity, accuracy, and system safety from the sensor to the monitoring system.
This unit is designed to work with the entire range of vibro-meter sensors and signal conditioners with current or voltage outputs, and is also compatible with industry-standard IEPE (Integrated Electronics Piezo Electric) vibration sensors. Its modular design, DIN-rail mounting, and pluggable screw-terminal connectors greatly facilitate system integration, installation, and maintenance.
2. Key Features and Benefits
Exceptional Galvanic Isolation Performance:
Between Sensor Side and Monitor Side: Provides reinforced isolation up to 4 kV RMS, effectively blocking ground loops and preventing high voltage from damaging expensive monitoring equipment.
Between Power Supply and Output Signal: Provides 50 V RMS isolation (floating output), eliminating the need for an external isolation power supply (e.g., APF19x), simplifying system design.
Powerful Noise Immunity:
Suitable for Explosive Atmospheres:
Available in certified explosion-proof versions (Ordering Option A2), with multi-national certifications including ATEX, IECEx, cCSAus, KGS, and EAC. Can be safely installed in Zone 2 / Division 2 hazardous areas and can power measurement chains installed in Zone 0/1 areas. Can replace external Zener barriers in intrinsic safety applications.
Flexible Power Supply and Signal Conversion:
Supports providing a constant voltage source (20 VDC) or a constant current source (8 mA) to the sensor side to accommodate different sensor requirements.
Offers μA to mV (for current signal transmission over long distances) and V to V (for voltage signal transmission over shorter distances) transfer functions, optimizing signal transmission for different application scenarios.
Wide Compatibility:
Fully compatible with the vibro-meter® product line: Supports IPC707/IPC704 charge amplifiers (for CAxxx accelerometers and CPxxx dynamic pressure sensors), IQS9xx/IQS4xx signal conditioners (for TQ9xx proximity probes), piezoelectric accelerometers with current output like CE134/CE281/CE31x, VE210 velocity sensors, etc.
Compatible with industry-standard IEPE-type sensors (constant-current voltage-output), such as CE620, PV660, and their predecessors.
Convenient Installation and Maintenance:
Removable Screw-Terminal Connectors: Can be plugged/unplugged from the unit body without tools, greatly simplifying wiring and installation.
DIN-Rail Mounting: Standard TH 35 rail mounting, saving cabinet space and facilitating integration.
No Ground Connection Needed: Simplifies installation requirements.
High Precision and Reliability:
Low offset and sensitivity drift with temperature, wide bandwidth, and high linearity ensure accurate signal transmission.
Robust polyamide housing with good environmental adaptability ensures long-term stable operation.
3. Model Number Analysis: 244-127-000-017-A1-B01
The model code 244-127-000-017-A1-B01 reveals the specific configuration of this device:
GSI127: Base product model, Galvanic Separation Unit.
A1: Indicates the Explosion-Proof Certified Version. The housing is grey, but the top screw-terminal connector for sensor-side signals is blue for identification.
B01: The key Ordering Option Code, defining the input/output characteristics:
Power Supply Mode: Provides a 20 VDC ±1 VDC constant voltage source to the sensor side.
Input Impedance: ≤ 30 Ω.
Input Dynamic Range: 0 to 20 mA.
Transfer Sensitivity: 1 V/mA ±1%. This means for every 1 mA change in sensor-side current, the monitor-side output voltage changes correspondingly by 1 V.
Output Offset Voltage (Zero): 7 VDC ±200 mVDC. This corresponds to a 5 mA DC quiescent current on the sensor-side signal line (e.g., the static operating current of some signal conditioners).
Typical Application: This configuration is specifically designed for long-distance current signal transmission, commonly used to connect IPC7xx charge amplifiers, CExxx accelerometers with current output, etc.
4. Application Scenarios & System Integration
The GSI127 plays a central "interfacing" role in vibration monitoring systems. According to the vibro-meter piezoelectric accelerometer manual, it is primarily integrated into the following four typical measurement chains:
1. Accelerometer with Connector + Separate Charge Amplifier (e.g., CA201 + IPC707):
The GSI127 powers the IPC707 charge amplifier and converts/isolates its output 4-20 mA current-modulated signal into a 2-10 VDC voltage signal sent to the monitoring system (e.g., VM600). The 7 VDC zero output of the B01 configuration corresponds to the 12 mA static output of an IPC707 (without diagnostics).
2. Accelerometer with Integral Cable + Separate Charge Amplifier (e.g., CA134 + IPC707):
Similar to the chain above, the GSI127 serves the same function of powering the charge amplifier and isolating/transmitting its current signal.
3. Accelerometer with Attached Signal Conditioner (e.g., CE134):
The accelerometer and signal conditioner are integrated together. The GSI127 directly powers this "sensing head" and reads its output current signal (e.g., μA/g), isolating and converting it to a voltage signal for the backend. This design allows the accelerometer head to be installed in high-temperature areas (up to 350°C) while the electronics are in a milder environment.
4. Accelerometer with Incorporated Signal Conditioner (e.g., CE310):
The signal conditioner is fully incorporated within the accelerometer. The GSI127 powers it via a junction box (JB XXX) and receives, isolates, and converts its current output signal.
Safety-Related Applications:
Thanks to its high level of galvanic isolation and explosion-proof certifications, the GSI127 is well-suited for machine protection systems requiring functional safety, ensuring that hazardous energy cannot propagate along the measurement chain in case of a fault.
5. Installation & Wiring Guidelines
Mounting Location: Should be installed in cabinets, control rooms, or safe areas with minimal vibration and within the specified ambient temperature range (0-55°C).
Power Supply: Provide a stable 18-30 VDC power source, ensuring sufficient current capacity.
Wiring:
Sensor-side cables (connecting the sensor/signal conditioner to the GSI127) should use shielded twisted pair and be routed away from high-power cables.
Monitor-side output signal lines should also use shielded cable, connected to the high-impedance voltage input terminals of the monitoring system.
The cable shield should be grounded at a single point, typically at the sensor end or signal conditioner end. At the GSI127 end, the shield should NOT be connected to the unit for optimal noise rejection.
Connection: Utilize its pluggable terminals: complete all wiring first, then plug the terminal block into the device body, which is very convenient for debugging and maintenance.
Grounding: Follow the relevant system guidelines for system grounding. The GSI127 itself does not require a dedicated ground connection.
