Description
MTL 8937-HN fiber extender counting module
8937-HN
As part of MTL’s 8900 Series, the 8937-HN serves as a galvanically isolated barrier for analog signals, specifically designed for use with 4-20 mA transmitters and other field devices. Its core purpose is to provide a safe interface between sensors or actuators in hazardous areas and control systems in safe areas, ensuring that electrical energy does not exceed the limits defined by intrinsic safety standards (e.g., IEC 60079). This makes it an essential component in safety instrumented systems (SIS), distributed control systems (DCS), and supervisory control and data acquisition (SCADA) networks operating in Zone 0/1 (gas) or Zone 20/21 (dust) environments.
| Label |
Specification |
| Model Number |
8937-HN |
| Brand |
MTL (Emerson Industrial Automation) |
| Type |
Intrinsically Safe Barrier (Analog Signal Isolation) |
| Input Signal |
4-20 mA (galvanically isolated) |
| Output Signal |
4-20 mA (isolated to safe area) |
| Power Supply |
20-30 V DC (via safe area connection) |
| Intrinsic Safety Rating |
Ex ia IIC T4 Ga / Ex iaD 21 T130°C Da (ATEX/IECEx certified) |
| Channel Count |
Single-channel (expandable via multi-channel racks) |
| Operating Temperature |
-20°C to 60°C |
| Mounting |
DIN-rail mountable (35 mm standard rail) |
| Dimensions |
101 mm (H) × 22.5 mm (W) × 115 mm (D) |
| Certifications |
ATEX, IECEx, UL, CSA, CE |
| Isolation Voltage |
250 V AC (between input, output, and power) |
8937-HN
The MTL 8937-HN incorporates dual galvanic isolation barriers to ensure that energy transmitted to the hazardous area remains below ignition thresholds. Its design includes 限流 (current limiting) and 限压 (voltage limiting) circuits, which automatically restrict power in the event of a fault, such as a short circuit or overvoltage in the safe area. This proactive protection meets the stringent requirements of IEC 60079-11, making it suitable for applications with high-risk explosive gases like methane or hydrogen.
With a precision voltage-to-current conversion error of less than 0.1%, the 8937-HN ensures accurate signal transmission without degradation. This is critical in processes like chemical reactor control, where slight deviations in sensor readings can lead to operational inefficiencies or safety incidents. The barrier’s high common-mode rejection ratio (CMRR) of 120 dB at 50 Hz further minimizes interference from electromagnetic fields (EMF) and radio frequency interference (RFI), ensuring stable performance in noisy industrial environments.
Built for longevity, the
8937-HN features a robust metal enclosure and conformal coating to protect against moisture, dust, and vibration. Its wide operating temperature range (-20°C to 60°C) makes it suitable for both indoor control panels and outdoor installations in harsh climates, such as offshore platforms or desert refineries. The module’s hot-swappable design allows for maintenance without powering down the system, reducing downtime during servicing—a key advantage in mission-critical applications.
8937-HN
In offshore drilling rigs, the MTL 8937-HN is used to isolate signals from pressure transmitters in hazardous zones (e.g., near wellheads) to the DCS in the control room. By limiting energy in the hazardous area, the barrier prevents sparks from igniting flammable gas leaks, while ensuring accurate pressure data is transmitted to operators. This enables real-time adjustments to drilling parameters, such as mud flow rate, to prevent blowouts and maintain operational safety.
In pharmaceutical plants, the
8937-HN safeguards processes involving flammable solvents (e.g., ethanol in drug synthesis). The barrier isolates level sensors in storage tanks (hazardous Zone 1) from the PLC in the safe area, ensuring compliance with Good Manufacturing Practice (GMP) and ATEX regulations. Its low power consumption (typically 0.5 W per channel) also aligns with energy-efficient design standards in cleanroom environments.
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