MTL Barries - MTL5041 - REPEATER POWER SUPPLY  - (4/20mA, for 2-wire transmitters)

The MTL5041 repeater power supply works by providing a floating DC power source to a 2-wire, 4-20mA transmitter in a hazardous area, which in turn is isolated from the safe area. It repeats the transmitter's current signal, transferring it to a separate floating circuit that drives a safe-area load with an isolated 4-20mA signal. This protects the safe area from the hazardous area and simplifies installation by not requiring a high-integrity earth ground.

How it works

• Hazardous area: The MTL5041 is powered by a 20-35V DC supply on the safe side and provides a floating DC supply to energize a 2-wire transmitter in a hazardous area.
• Signal transfer: The transmitter uses the power from the MTL5041 to create a 4-20mA signal based on the measured process variable.
• Safe area: The MTL5041 receives this 4-20mA signal from the transmitter and repeats it as an isolated output signal to drive a load (e.g., a recorder or controller) in the safe area.
• Isolation: The unit provides galvanic isolation, meaning there is no direct electrical connection between the hazardous and safe area circuits. This ensures that any fault or energy in the hazardous area does not transfer to the safe area

Key features    

• Application: Used to power 2-wire transmitters in hazardous locations, repeating the signal to the safe area.
• Power: Operates on a 20-35V DC supply and provides a 16.5V minimum at 20mA to the transmitter.
• Output: Drives a safe-area load with a 0-1kΩ resistance.
• Safety: Acts as a galvanic isolator, simplifying installation and eliminating the need for a high-integrity earth ground required by some other barriers.

The MTL MTL5041 operates as a repeater power supply/galvanic barrier that provides intrinsically safe isolation for a 2-wire 4-20mA transmitter located in a hazardous area. It isolates the hazardous-area circuit from the safe-area control equipment, eliminating the need for a high-integrity earth ground.

Core Working Principle

The MTL5041's working principle involves three main functions:

• Power Supply: The unit receives power from a safe-area 20-35V DC supply. It generates a fully-floating, intrinsically safe DC supply (approx. 16.5V at 20mA) which is sent to the 2-wire 4-20mA transmitter in the hazardous area, energizing the transmitter.
• Signal Reception: The hazardous-area transmitter modulates the current in the loop between 4mA and 20mA (or 0-24mA including over-range) to represent the process measurement.
• Signal Isolation and Repetition: The MTL5041 receives this current signal and, using a transformer-coupled circuit, galvanically isolates it to eliminate ground loop problems and protect sensitive control equipment from dangerous voltages. It then repeats this current signal in a separate, floating safe-area circuit to drive a safe-area load, such as a PLC or control system input, with an isolated 4-20mA output.

Key Features Contributing to its Operation

• Intrinsic Safety: The core function is to limit the energy (voltage and current) that can enter the hazardous area, preventing the ignition of an explosive atmosphere, which is a primary advantage over non-IS techniques.
• Galvanic Isolation: Isolation is maintained between the hazardous area, safe area, and power supply terminals (tested at 2200V rms minimum), ensuring safety and preventing common-mode noise or ground loop errors from affecting the signal integrity.
• High Accuracy: The design ensures high accuracy and low ripple transmission of the current signal with a transfer accuracy typically better than 20µA.

 Full Datasheet