Product Details
The Yokogawa EXA PH202, also cataloged as the PH202 2-Wire pH/ORP Analyzer, operates as a dedicated hardware component for continuous liquid analytical measurement and signal conversion within Yokogawa CENTUM VP DCS and fieldbus communication networks.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | EXA PH202 |
| Brand | Yokogawa |
| Origin | Japan |
| Measuring Principle | Glass electrode method |
| Input Ranges |
pH: -2 to 16 pH ORP: -1500 to 1500 mV rH: 0 to 55 rH Temperature: -30 to 140 deg C |
| Output Ranges |
pH: Span 1 to 20 pH ORP: Span 100 to 3000 mV rH: Span 2 to 55 rH Temperature: Span 25 to 200 deg C |
| Output Signal |
4-20 mA DC loop-powered, isolated from input Failure limits: 21 mA (burn up), 3.6 mA or 3.9 mA (burn down) |
| Communication | HART, PROFIBUS-PA, FOUNDATION Fieldbus H1 |
| Temperature Compensation | -30 to 140 deg C; Automatic or manual compensation via Pt100, Pt1000, 3 kohm RTC, 5.1 kohm PTC, 8.55 kohm NTC, 350 ohm PTC, 6.8 kohm PTC, or 10 kohm PTC sensors |
| Display | Custom LCD, 3 1/2 digits, 12.5 mm character height |
| Power Supply | Nominal 24 VDC loop-powered (17 to 40 VDC for PH202G) |
| Operating Temp | -10 to 55 deg C |
| Operating Humidity | 10 to 90 % RH (Non-condensing) |
| Accuracy |
pH: +/-0.01 pH ORP: +/-1 mV |
| Linearity |
pH: +/-0.01 pH ORP: +/-1 mV |
| Repeatability |
pH: +/-0.01 pH ORP: +/-1 mV |
Process Control Signal Integration & Fieldbus Isolation
The unit features a differential input amplifier equipped with equipotential screening to mitigate ground loop interference across long-distance sensor cable runs. Automatic or manual temperature compensation utilizes standard RTD and thermistor curves (including Pt100, Pt1000, and NTC options) to apply real-time Nernst equation adjustments alongside user-configurable process coefficients. Onboard digital communication options—HART, PROFIBUS-PA, or FOUNDATION Fieldbus H1—allow direct transmission of primary variables, secondary temperature metrics, and sensor diagnostic states over standard 4-20 mA loop-powered wiring. Channel isolation prevents noise propagation between the high-impedance measurement inputs and field-side PLC/DCS analog input interfaces.
Frequently Asked Questions
Q: How does the analyzer handle loop-powered signaling under primary sensor fault conditions?
A: The transmitter defaults to configurable fault levels on its 4-20 mA loop output. Burn-up drives the output to 21 mA, while burn-down drops the signal to 3.6 mA (standalone mode) or 3.9 mA (when HART or fieldbus distributor communications are active).
Q: What are the input impedance requirements and ground loop mitigation features for the pH glass electrode inputs?
A: The device provides dual high-impedance inputs combined with a differential amplifier and equipotential screening, preventing parasitic ground currents from skewing the millivolt potential across the glass electrode and reference junction.
Field Installation Guidelines
- Sensor Cable Shielding: Route the high-impedance glass and reference electrode wiring through grounded metallic conduit. Connect the equipotential screen directly to the dedicated instrument ground terminal to minimize electromagnetic interference.
- Wiring & Loop Impedance: Verify that supply voltage at the terminal blocks remains within 17 to 40 VDC under load. Account for total loop resistance (including DCS input card resistance and HART communicator load limits) to prevent voltage drops below 17 VDC.
- Hazardous Area Mounting: When deploying intrinsically safe configurations (FM, CSA, or CENELEC certified), install appropriate galvano-isolated safety barriers or zener barriers in accordance with regional hazardous location wiring diagrams.
Additional Information
- 100% Genuine Parts: All products are original and authentic, ensuring reliable industrial performance.
- 30-Day Refund Guarantee: Return any in-stock item within 30 days in original, unopened packaging for a full refund (excluding shipping and fees).
- 12-Month Warranty: Covers defects in materials or workmanship; excludes misuse, normal wear, or unauthorized modifications.
- Worldwide Shipping: We ship via USPS, UPS, FedEx, and DHL. Delivery times vary by country and may be subject to customs or import fees.
- Support & Contact: Technical and warranty assistance is available anytime. Contact us here: Contact.
- Purchase Guidance: Check product specifications and compatibility carefully before ordering to ensure proper application.
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