Description
Product Introduction & Engineering Value
When a control valve refuses to respond correctly, engineers often suspect the actuator or field wiring. In many legacy systems, the actual culprit is the analog output module that has drifted after years of continuous operation.
The GE IC693ALG390 is a 2-channel analog voltage output module designed for the Series 90-30 PLC. It converts PLC digital commands into stable analog voltage signals for VFDs, valve positioners, recorders, and other field devices. Factory calibration, optical isolation, and a fast channel update rate make it suitable for demanding industrial control applications.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | GE Intelligent Platforms |
| Model | IC693ALG390 |
| Product Family | Series 90-30 |
| Module Type | Analog Voltage Output |
| Output Channels | 2 |
| Output Range | -10 VDC to +10 VDC |
| Resolution | 2.5 mV (1 LSB) |
| Accuracy | ±5 mV at 25°C |
| Channel Update Rate | Approximately 5 ms |
| Isolation | 1500 VAC field-to-logic optical isolation |
| External Supply | 18-30 VDC |
| Maximum Output Load | 5 mA (minimum 2 kΩ load) |
| Mounting | Any Series 90-30 I/O slot |
| Backplane Power | +5 VDC and +24 VDC |
Field Application & The “Trench” Experience
A refinery maintenance crew noticed a reactor temperature control valve moving erratically after a planned shutdown. Instrument technicians verified the positioner, recalibrated the valve, and even replaced the field cable without success. During troubleshooting, they injected a reference signal directly into the valve positioner and confirmed normal operation. The fault was traced to an aging IC693ALG390 whose output drifted under load. Installing a replacement module restored accurate valve positioning within minutes, allowing production to resume without modifying the PLC program.
Typical applications include:
- Catalytic Cracking Unit control valve positioning
- Boiler combustion air damper control
- Variable Frequency Drive speed reference outputs
- Chemical reactor dosing control
- Industrial furnace burner modulation
IC693ALG390
IC693ALG390
Transparency SOP: QA & Testing
Before shipment, every module undergoes documented verification procedures:
- ✔ Visual inspection for PCB damage, connector wear, corrosion, and housing condition
- ✔ Model number and hardware revision verification
- ✔ Installation in a Series 90-30 PLC test rack
- ✔ Individual channel testing using calibrated voltage measurement equipment
- ✔ Verification of output accuracy across the complete ±10 V operating range
- ✔ Isolation and diagnostic indicator verification
- ✔ ESD-safe packaging with protective cushioning
For New Surplus inventory, factory packaging and unused condition are verified. Refurbished units receive additional functional and burn-in testing before release.
The Veteran’s Tech Trap Guide
⚠️ Don’t Ignore the External 24 VDC Supply
The IC693ALG390 requires proper external power in addition to the PLC backplane. Missing or unstable 24 VDC can produce incorrect analog outputs even though the PLC CPU appears healthy.
⚠️ Measure Under Load
Reading ±10 V with a high-impedance multimeter does not guarantee normal operation. Always verify output while connected to the actual field device.
PRO TIP: Before replacing the module, compare the commanded PLC register value with the measured output voltage. If they disagree consistently, the output electronics—not the application program—is usually responsible.
⚠️ Check Instrument Grounding
Poor shield termination or shared analog grounds can introduce signal instability that closely resembles hardware failure.
Dynamic FAQ
Q1. What devices can the IC693ALG390 control?
It is commonly used to provide analog voltage references for valve positioners, variable frequency drives (VFDs), chart recorders, servo controllers, and other equipment accepting a ±10 VDC input.
Q2. Does this module provide current outputs?
No. The IC693ALG390 is specifically designed for voltage output applications. If your system requires configurable current outputs such as 4–20 mA, another Series 90-30 analog output module should be selected.
Q3. Can I replace the module without modifying the PLC program?
In many maintenance situations, yes. If the replacement has the same part number and hardware compatibility, existing logic typically remains unchanged. A functional checkout is still recommended after installation.
Q4. Is the module electrically isolated?
Yes. The module incorporates 1500 VAC optical isolation between the field wiring and the PLC logic side to reduce electrical noise and improve system reliability.
Q5. Are New Surplus modules truly unused?
Yes. New Surplus inventory consists of unused OEM inventory that has never been installed in production equipment. Packaging condition may vary depending on storage history.
Q6. Is warranty coverage available?
Warranty terms depend on inventory condition (New Surplus or Refurbished) and the supplier’s policy. Request warranty documentation and test reports before purchase.
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