MTL Barries - MTL5018 SWITCH/ PROXIMITY DETECTOR INTERFACE (two-channel, with line fault detection and phase reversal

The MTL5018 is a two-channel switch/proximity detector interface that allows two hazardous-area devices to control two safe-area loads. Its working principle is to isolate the hazardous area from the safe area, providing two relay outputs that are energized when the input devices (switches or proximity detectors) are active. The module includes features like user-selectable Line Fault Detection (LFD) to monitor for open or short circuits in the field wiring and independent phase reversal for each channel.

Detailed breakdown of the working principle:

• Signal Isolation: The core principle is a two-channel, two-wire interface with an intrinsic safety barrier, which provides electrical isolation between the hazardous and safe areas.
• Input and Output:

• It has two input channels that receive signals from switches or proximity detectors in a hazardous area.
• These inputs drive two independent relay outputs in the safe area, which can control external loads

• Line Fault Detection (LFD):

• A user-selectable feature that detects open or short circuits in either of the two field circuits.
• When a fault is detected, the module de-energizes the corresponding relay output and a red LED indicates the fault status.

• Phase Reversal:

• An independent and user-selectable feature for each channel that can reverse the phase of the output signal. This is useful for signaling alarm conditions.

• Input Signal Conditioning:

• The module is designed to work with both switches and proximity detectors, conforming to standards for
• proximity detectors like NAMUR/DIN 19234.It applies a 7 to 9V DC to the sensor input and typically has a hysteresis of 200A.

• Relay Outputs:

• Each channel has a single-pole, changeover (SPCO) relay contact.
• These contacts have ratings such as 250VAC ,2A or 40VDC,2A. 

The MTL5018 is a two-channel switch/proximity detector interface that acts as a safety barrier, allowing equipment in a safe area to be controlled by switches or proximity detectors located in a hazardous area. Its primary working principle revolves around providing intrinsic safety through galvanic isolation.

Working Principle

The MTL5018 operates by limiting the amount of electrical energy (voltage and current) that can pass from the safe area (where the control system is located) into the hazardous area (where flammable gases or dust may be present). This ensures that even under fault conditions, the energy level in the hazardous area remains too low to ignite a potentially explosive atmosphere.
Key aspects of its operation include:

• Galvanic Isolation: The unit provides total AC and DC isolation between the input (hazardous area), output (safe area), and power supply terminals. This means there is no direct electrical connection, preventing dangerous voltages from the safe area from reaching the hazardous area.
• Signal Conversion: It takes inputs from simple switches or proximity detectors in the hazardous area and converts them into reliable signals that can be used by standard industrial control systems (like PLCs or other loads) in the safe area.
• Relay Outputs: For each of the two channels, the interface provides a relay output in the safe area. The state of this safe-area relay changes in response to the state of the input switch or detector in the hazardous area.
• Independent Phase Reversal: The user can independently configure the phase (normally open or normally closed state) of each channel's output relay. This allows an alarm condition to be signaled for either the open or closed state of the sensor, providing flexibility in system design.
• Line Fault Detection (LFD): When this optional feature is selected, the module continuously monitors the field wiring for open or short circuits. If a fault is detected, it is signaled as an alarm condition in the safe area, ensuring system integrity. Resistors must be fitted to the switch contacts in the hazardous area for this feature to work with contact inputs.

In essence, the MTL5018 functions as an isolating interface unit that reliably translates signals between hazardous and safe areas while strictly adhering to intrinsic safety standards to prevent explosions. More detailed specifications and installation information can be found in the product's official datasheet.

 Full Datasheet