The MTLx546 accepts a 4/20mA floating signal from a safe-area controller to drive a current/pressure converter (or any other load up to 800Ω) in a hazardous area. For HART valve positioners, the module also permits bi-directional transmission of digital communication signals. Process controllers with a readback facility can detect open or short circuits in the field wiring: if these occur, the current taken into the terminals drops to a preset level.

The MTL4546C and the MTLx546Y are very similar to the MTLx546 except that they provide open circuit detection only (i.e. no short-circuit detection).

• Number of channels: One
• Location of I/P converter: Zone 0, IIC, T4-6 hazardous area if suitably certified Div. 1, Group A, hazardous location
• Working range: 4 to 20mA
• Digital signal bandwidth: 500Hz to 10kHz
• Maximum load resistance: 800Ω (16V at 20mA)
• Minimum load resistance: 90Ω (short-circuit detection at < 50Ω)
• Output resistance: > 1MΩ
• Under/over range capability: Under range = 1mA, Over range = 24mA (load ≤ 520Ω)
• Input and output circuit ripple: < 40µA peak-to-peak
• Transfer accuracy at 20°C: Better than 20µA
• Temperature drift: < 1.0µA/°C
• Response time: Settles within 200µA of final value within 100ms
• Communications supported: HART
• LED indicator: Green: power indication
• Maximum current consumption (with 20mA signals into 250Ω load): 35mA at 24V dc
• Power dissipation within unit (with 20mA signals into 250Ω load): 0.8W at 24V
• Safety description: Uo =28V Io =93mA Po =651mW Um = 253V rms or dc