Honeywell MC-GHAO21 51305869-175 Analog Output FTAs Module

The MC-GHAO21 51305869-175 is a redundant model Analog Output (AO) Field Termination Assembly (FTA) that is designed to isolate up to sixteen 4-20 mA signals. These signals can drive current-to-pressure (I/P) transducers, position actuators, or any load with a resistance of 870 ohms or less. The FTA is associated with an Analog Output Input/Output Processor (IOP). Here’s a summarized breakdown of the functions and features of this model:

1. Fault-line Detection: If an open or short circuit occurs in the field wiring, the resistance sensed at the input to the Galvanic Isolation Module will be high. This enables the associated 4-20 mA Analog Output IOP to detect the open or shorted field circuit. It will then report a soft failure to the user.
2. Signal Connectors: The redundant FTA model has:
   • Two 50-pin connectors for interfacing with one or two IOPs.
   • A 20-pin connector for interfacing with an external HART multiplexer.
   • Two 2-pin power connectors for interfacing with the GI/IS Power Distribution Panel.
3. Field Wiring Output Signals: The FTA generates 4-20 mA signals to control field devices. These devices are galvanically isolated from other circuits. The load resistance for these signals should not exceed 870 ohms. The dynamic impedance of the signal output is greater than 1 megohm.
4. Calibration Terminals: Four screw terminals are provided on the FTA, consisting of two pairs for calibrating the primary and secondary IOPs. A touch pad is available to initiate the calibration procedure in the primary or secondary IOP.
5. Indicators:
   • A green indicator on the FTA lights up when the primary IOP (A) is active.
   • Green indicators on each Galvanic Isolation Module illuminate when power is applied to the module.
6. Current Consumption:
   • Both FTA models consume 928 mA at 24 Vdc when all outputs have a 20 mA signal.
   • The FTA’s power dissipation is 21.6 watts when all outputs provide 20 mA of current.
7. Isolation and Safety:
   • The FTA provides 250 Vac isolation between the safe-side and hazardous-side. The Galvanic Isolation Module divides these sides.
   • Safety description for the output of each Galvanic Isolation Module includes:
     • Maximum voltage of -28 volts.
     • Maximum resistance of 240 ohms.
     • Maximum current of 116 milliamps.
     • Voltage limit (Um) of 250 Vrms AC or DC.