Models: 671T: Single I/O channel 672T: Dual I/O channel 674T: Quad I/O channel These units receive 4-20mA process current inputs and provide isolated 4-20mA output signals. Power is derived from the input signal current. Each channel operates independently and is isolated from the others to prevent interaction between channels. For easy troubleshooting, each unit has LEDs and diagnostic test points. Fault LEDs identify output open loop conditions and load compliance problems. The precision 10 ohm sense resistor enables monitoring of the output signal without disturbing field wiring. Input / Output Ranges: 4 to 20mA DC input 4 to 20mA DC output Power Requirement: Loop-powered (power derived from input signal current) Approvals: CE marked. UL, cUL listed Class I; Division 2; Groups A, B, C, D

Performance Specifications

IMPORTANT: The 671T transmitter is an input loop powered current isolator. Its input voltage burden is normally a function of its output voltage drop and is computed as 4.9V+Iout*Rout. If the output load resistance Rout is excessive relative to the input loop voltage, or Rout is open-circuited, the input voltage burden may increase up to the limit of available input loop voltage. Consequently, if there are any loop-powered transmitters connected in series in the 671T input loop, this output loop fault can pinch-off excess input loop voltage, reducing the available voltage to power any series-connected transmitters in the loop, potentially causing them to lose regulation of the input loop current. You could select a different current isolator than 671T, or a different series transmitter that is separately powered to avoid this fault condition. Reference Test Conditions: Input/Output current: 4 to 20mA; output load 250 ohms; 77°F (25°C) Input: 4 to 20mA input (each channel) Input Burden: The voltage drop is a function of the input current and load resistance and is calculated as follows: Input Voltage Drop = 4.9V DC + (0.0212A x Rload)  Example:  For Rload = 250 ohms, Vdrop = 10.2V DC Output: 4-20mA DC output (each channel) Output Load: 0 to 525 ohms Accuracy: Better than ±0.1% of output span. Error includes the combined effects of isolator repeatability, hysteresis, terminal point linearity and adjustment resolution. Calibration: One 15-turn potentiometer per channel, accessible from front of the unit. Ambient Temperature Effect: Less than ±0.01% of output span per °F (±0.018% per °C) over the ambient temperature range for reference test conditions. This specification includes the combined effects of zero and span over temperature. Output Ripple: Less than ±0.1% of the maximum output span Bandwidth: -3dB at 2.2Hz, typical Response Time: For a step input, the output reaches 98% of output span in less than 300mS, typical, into 250 ohms. Noise Rejection: Common mode: 110dB at 60Hz, typical Diagnostics: LED fault indicator: Lights for output open loop detection or load compliance problem. Field test points: An internal 10 ohm sense resistor provides test points for monitoring the output signal current during field maintenance with a voltmeter.


Ambient Temperature: Operating: -25 to 70°C (-13 to 158°F) Storage: -40 to 85°C (-40 to 185°F) Relative Humidity: 5 to 95% Power Requirement: Power is derived from the input signal loop. In the event of an open output circuit, the input loop voltage drop is limited below 20V, nominal. Isolator has reverse polarity protection. Isolation: Inputs, outputs, and individual channels are isolated from each other for common-mode voltages up to 250V AC, or 354V DC off ground, on a continuous basis (will withstand 1500V AC dielectric strength test for one minute without breakdown). Radiated Field Immunity (RFI): Designed to comply with EN61000-4-3 Level 3 (10V/m, 80 to 1000MHz AM and 900MHz keyed) and European Norm EN50082-1 Electromagnetic Field Immunity (EMI): Less than ±0.25% of output span effect under the influence of electromagnetic fields from switching solenoids, commutator motors, and drill motors Electrical Fast Transient (EFT): Complies with EN61000-4-4 Level 3 (2KV) and European Norm EN50082-1 Surge Immunity: Complies with EN61000-4-5 Level 3 (2KV) and European Norm EN50082-1 Electrostatic Discharge (ESD): Complies with EN61000-4-2 Level 3 (8KV air, 4KV direct to the enclosure port) and European Norm EN50082-1 Radiated Emissions: Meets or exceeds European Norm EN50081-1 for Class B equipment Approvals: CE marked, UL & cUL listed Hazardous Locations: Class I: Div. 2; Groups A, B, C, D


Enclosure: Case: Self-extinguishing NYLON type 6.6 polyamide thermoplastic UL94 V-2 NEMA Type 1 enclosure Connectors (Removable Terminal Blocks): Wire Range: AWG #14-22 (AWG #12 stranded only) Printed Circuit Boards: Military grade FR-4 epoxy glass circuit board Dimensions: 1.05W x 4.68H x 4.35D inches 26.7W x 118.9H x 110.5D millimeters Shipping Weight: 1 pound (0.45 Kg) packed

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    671T, 672T, 674T: Multi-Channel, Two-Wire Isolators

    • 4 to 20mA DC input
    • 4 to 20mA DC output
    • Single, dual, or quad I/O loop-powered isolators
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