MTL F271-IS

Description

Technical Specifications

• Channel Configuration: Single independent signal channel (one barrier per field digital loop)
• Supply Voltage (Safe Side): Nominal 24 VDC; allowable operating range 20 VDC – 35 VDC
• Intrinsic Safety Energy Limitation Parameters (Hazardous Side):
  • Maximum Open Circuit Voltage (Voc): 22 VDC
  • Maximum Short Circuit Current (Isc): 100 mA
  • Maximum Permissible Inductance (Li): 10 mH
  • Maximum Permissible Capacitance (Ci): 0.1 μF
• Galvanic Isolation Rating: 250 VAC dielectric strength between safe area and hazardous area circuit
• Response Time: ≤10 ms signal transmission delay
• Power Consumption: 0.5 W maximum static power draw at nominal 24 VDC supply
• Environmental Ratings:
  • Operating Temperature: -20 °C ~ +60 °C
  • Storage Temperature: -40 °C ~ +85 °C
  • Protection Class: IP20 (safe-area cabinet mounting only)
• Mechanical Dimensions: 100 mm (H) × 60 mm (D) × 16 mm (W)
• Net Weight: 0.15 kg
• Certifications: ATEX II 1G Ex ia IIC, IECEx ia IIC, UL intrinsic safety certification, EN 60079-11, EN 61010-1

Function Features

1. Galvanic transformer isolation completely separates safe-area control system circuit and hazardous-area field instrument circuit to eliminate ground loop fault energy transfer
2. Precision voltage clamping and current limiting circuits restrict hazardous-side maximum voltage/current to non-ignition levels for II C hydrogen hazardous gas environments
3. Reverse power supply polarity protection; barrier maintains full safety performance with reversed 24 VDC supply wiring
4. Per-channel hardware overvoltage transient protection to suppress lightning surge energy entering hazardous zone wiring
5. Compact 16 mm narrow DIN rail form factor for high-density barrier packing inside safe-area control cabinets
6. Screw terminal connection for both safe-area control wiring and hazardous-area field wiring; clear terminal labeling for zone separation identification
7. Passive signal transmission with zero signal attenuation for binary digital switch, proximity sensor and solenoid valve loops

Material Composition

• Outer Housing: UL94-V0 flame retardant polycarbonate plastic
• Isolation Core Component: High-reliability isolation transformer with reinforced insulation winding
• Circuit Board: FR4 fiberglass PCB with tin-plated signal traces
• Safety Limiting Components: Precision zener diodes, low-temperature drift wirewound current-limiting resistors, transient suppression TVS diodes
• Terminal Blocks: Copper nickel-plated corrosion-resistant screw terminals

Structural Characteristics

• Ultra-narrow 16 mm width DIN rail mount design for maximum cabinet channel density
• Front panel clearly labeled terminal partitions separating SAFE SIDE (cabinet zone) and HAZARDOUS SIDE (field explosion zone) wiring terminals
• Integrated rear DIN rail spring locking clip for rapid installation and removal without tools
• Fully encapsulated internal circuit assembly to prevent dust ingress and component mechanical displacement
• No front panel LED indicators; passive barrier design without power-consuming diagnostic circuits

Working Principle

1. Safe-area 24 VDC digital signal from control system I/O module enters barrier safe-side circuit; isolation transformer transfers signal energy without conductive electrical connection between safe and hazardous zones
2. Zener voltage clamping diodes and fixed current-limiting resistors continuously restrict maximum voltage and current available to hazardous-side field wiring to certified non-ignition energy levels for Ex ia IIC gas groups
3. Transient surge TVS diodes absorb lightning-induced voltage spikes before energy can propagate to hazardous field wiring
4. Reinforced transformer insulation barrier eliminates conductive fault path between safe-area high-voltage power circuits and explosion-prone field instrumentation
5. All energy limiting components are fully encapsulated to prevent mechanical damage altering safety performance parameters during long-term operation

Advantage Highlights

1. Ex ia IIC certification permits direct connection to Ex Zone 0 hazardous field instruments (highest intrinsic safety zone rating)
2. Full galvanic isolation eliminates ground loop induced signal distortion and hazardous energy transfer between unequal ground potentials
3. Ultra-narrow 16 mm form factor reduces total cabinet space requirement for large-scale hazardous area instrument systems
4. Reverse polarity protection eliminates wiring commissioning error risk without barrier damage or safety performance degradation
5. Passive signal transmission design requires no auxiliary power supply for barrier operation, reducing cabinet power wiring complexity
6. Wide operating temperature range adapts to unconditioned industrial safe-area control cabinets

Applicable Industries

Oil & gas refinery hazardous area instrument signal isolation, petrochemical plant Ex Zone 0/1 digital sensor loops, offshore platform gas detection wiring, pharmaceutical solvent batch process monitoring, chemical fertilizer plant explosive gas zone instrumentation, underground mining methane detection signal circuits

Installation Requirements

1. Mandatory installation inside non-hazardous safe-area IP20 control cabinet only; barrier cannot be mounted within Ex Zone 0 / Zone 1 hazardous areas
2. Mount on standard 35 mm DIN rail with minimum 3 mm horizontal spacing between adjacent barriers for heat dissipation
3. Strict physical separation of safe-side cabinet wiring and hazardous-side field wiring inside cabinet trunking; separate cable conduits mandatory
4. Hazardous-area field wiring must use certified intrinsically safe cable with dedicated earth screening
5. Cabinet ambient humidity controlled at 5% – 95% non-condensing
6. Install external cabinet surge protection device on all hazardous-area cable entry points to cabinet
   

   Usage Precautions

   1. Never connect safe-side supply voltage exceeding 35 VDC; overvoltage destroys internal safety limiting components and voids intrinsic safety certification.
   2. Hazardous field cable total capacitance and inductance must not exceed certified maximum Ci=0.1 μF, Li=10 mH; excess cable parameters create ignition risk.
   3. Strictly separate safe-side and hazardous-side wiring terminals; cross wiring leads to loss of intrinsic safety protection.
   4. Do not modify internal circuit encapsulation or disassemble unit; tampering invalidates ATEX/IECEx safety approvals.
   5. Terminal screw tightening torque limited to 0.5 N·m; over-torquing cracks plastic housing and breaks PCB traces.
   6. Annual insulation resistance test between safe and hazardous circuits required to maintain safety compliance.
   7. For Ex ia IIC hydrogen environments, only certified IS field devices matching barrier energy limits are permitted for connection.