MTL Barries - MTL7796 + Vibration probes

The MTL7796+ is a Zener barrier that works by limiting the energy transferred into a hazardous area to a level that cannot cause an explosion. It uses diodes to shunt any excess energy to the ground, protecting the intrinsically safe circuits from faults in the safe area. It is designed to be mounted on a DIN rail and provides a safe and simple way to connect field devices in hazardous locations to control systems.maintenance

Key working principles:

• Energy limitation: The barrier is connected in series with the signal lines between the safe and hazardous areas. It contains a combination of Zener diodes and resistors that act as a shunt to the ground.
• Hazardous area protection: If a fault occurs in the safe area (like a short circuit or voltage surge), the barrier redirects the excess energy to the ground, preventing it from reaching the hazardous area and creating a spark.
• Signal pass-through: For normal operation, the barrier allows the electrical signal (e.g., a 4-20mA signal) to pass through to the control system.
• Intrinsically safe design: The barrier ensures that the connected equipment in the hazardous area remains intrinsically safe, meaning it is not capable of igniting explosive atmospheres even in the event of a fault.
• DIN rail mounting: The MTL7796+ clamps onto standard DIN rails, which simplifies installation, maintenance, and allows for easy removal of terminals to create a loop disconnect.
• Bussed power feed (optional): The MTL7700 series, which includes the MTL7796+, features an optional power feed facility that uses a power feed module (like the MTL7798) and a power comb to supply power to multiple barriers without extra wiring.

The MTL7796+ is an intrinsically safe (IS) shunt-diode safety barrier that prevents explosions in hazardous areas by limiting the electrical energy that can enter those areas.

Vibration probes

Working Principle

The core principle of the MTL7796+ is to safely divert excess electrical energy to the earth (ground) in the event of an electrical fault in the safe area. It uses passive components to achieve this protection:

1. Zener Diodes: The barrier contains two stages of pulse-tested Zener diodes. These diodes are connected in a way that, under normal operating conditions, they allow the signal to pass through with minimal effect. However, if the voltage from the safe area exceeds a specific, safe threshold, the Zener diodes begin to conduct, "shunting" (diverting) the excess voltage to a reliable IS earth connection.
2. Resistor: An "infallible" terminating resistor is included in the circuit. This resistor limits the current that can flow into the hazardous area, ensuring it stays below the level required to create a spark or hot surface capable of igniting a flammable atmosphere.
3. Fuse: A fuse provides protection for the diodes themselves. In the event of a significant fault, the fuse will blow, isolating the circuit and ensuring the continued safety of the system.

The design ensures that even if one stage of voltage limitation fails, the second stage maintains safety.

Key Function

 Full Datasheet