The T703 has 16 overlapping input ranges which are field selectable via top-accessed DIP switches (see Table 1). The T703can accept input voltage spans from 20mV to 200 volts and input current spans from 1mA to 50mA. Bipolar selection modifies the unipolar range to include a negative offset (e.g. 200V becomes ±100V). The T703 provides 1000Vrms of transformer-coupled isolation and 120VAC continuous input overload protection. The top-mounted super bright LED illuminates when the loop current is above 3.3mA. Standard surface mount RFI filters reject walkie-talkie interference and noise. Current output is in proportion to the selected voltage or current input.

The T703 has 80% zero “turn-up” and 80% span “turn-down” adjustments within any user-selected input range. For example, Range 11 of Table 1 specifies 0 to 100V with a minimum span of 20V (100V - 20V = 80V, or 80%). This 80% adjustability allows the user to field-calibrate the unit from the maximum (0 to 100V) down to any minimum (20V) span (e.g. 25V to 45V) within the selected 0 to 100V range. The same is true in any user-selectable range: all spans are field adjustable from 20% (minimum span) to 100% of the specified range.

Application

The T703 is useful in any application requiring an isolated two-wire loop current from a DC source. Typical applications include long distance signal transmission and the elimination of ground loops. The output of the T703 can be used to drive a digital meter for direct display, or to interface with a computer for monitoring and control applications.

The model T703 is FM approved for intrinsically safe operation, entity, Classes I, II, III, Division 1, Groups A-G and Nonincendive, Class I, Division 2, Groups A-D hazardous when installed per manufacturer’s drawing 790-0028-00.

Input Span Range (Min/Max)   

See Table 1.

• Note: Bipolar span selection will move unipolar range to reflect negative offset (e.g., 20mA = ±10mA)

Input Inpedance 

• Ranges 1-4: 5M Ohms, typical

• Ranges 5-12: >200k Ohms, typical

• Ranges 13-16: 20 Ohms, typical

Output Span (fixed)   

4-20mA

Minimum Output Current   

3.3mA, typical

Maximum Output Current   

24mA, typical

Supply Voltage Range   

13 to 80VDC

Maximum Change In Supply Voltage Effect 

0.05% of Span

Maximum Changes In Load Effect   

0.05% of Span

Loop Voltage Drop   

13VDC @ 20mA

Output Current Limiting     

• Active: 27mA

• Fused (fixed): 0.25A

Entity Parameters   

• VOC = 33VDC, ISC = 178.5mA,

• CI = 12nF, LI = 0uH

Stability 

• Zero: ± 0.02% of span/°C, max. (±0.05%, bipolar)

• Span: ±0.03% of span/°C, max.

Accuracy     

• Overall (Includes best straight line Linearity, Hysteresis & Repeatability @ 25°C): ±0.2% of any adjusted span, max.

• Linearity: ±0.1% of range

• Hysteresis & Repeatability: ±0.05% of range

• Settability: ±0.05% of range