Why the RFQ Governs Both Sides
The request for quotation (RFQ) — the technical specification — is the document that governs the behavior of both supplier and buyer. It defines what will be delivered, how it will be accepted, and what evidence settles a dispute during the warranty period. A vague RFQ invites ambiguous bids: the buyer compares apples to oranges, and acceptance becomes a negotiation rather than a verification. Chapter 9.4 of the L-PAS DGA whitepaper lists the specification items that actually matter. This article turns that list into a ten-item checklist you can adapt to your procurement.
The 10 Specification Items That Matter
The table below consolidates the whitepaper’s recommended RFQ items. Each one maps to a measurable acceptance criterion.
| # | Specification item | What to require |
|---|---|---|
| 1 | Gases detected | Specify gas types and whether moisture is included (e.g., 9-gas + moisture; 7-gas + moisture + O2/N2) |
| 2 | Detection limit | Gas by gas, especially C2H2 (commercial L-PAS ≤0.1 ppm) |
| 3 | Measurement range & accuracy | Each gas range covers normal to fault concentrations; repeatability and uncertainty metrics |
| 4 | Measurement cycle & response | Cycle range (near-real-time / hourly); T63 step-response time |
| 5 | Oil-gas separation | Degassing principle, equilibration time, oil-circuit safety (consumes no oil, does not alter oil flow) |
| 6 | Environmental adaptability | Outdoor enclosure rating (e.g., IP55), wide temperature range (e.g., −40 to +55 °C), electromagnetic compatibility |
| 7 | Communication & integration | MODBUS RTU/TCP, IEC 61850, IEC 60870-5-104, DNP3.0, RS485; 4–20 mA for backup only |
| 8 | Certification & testing | A1-level evaluation, technical appraisal, international third-party audit, metrological verification certificate |
| 9 | Cybersecurity | Encryption, access control, and data integrity following the IEC 62443 framework |
| 10 | Warranty & maintenance | Warranty period, calibration interval and standard-gas traceability, spares supply, remote maintenance support |
Detection Limits: The Item Most RFQs Get Wrong
Many RFQs specify “high sensitivity” without a number. Detection limits must be written gas by gas, and the critical one is C2H2 — it is generated in significant quantities only at relatively high discharge energies, so the ability to see it early is what protects a transformer from an arcing fault. Commercial L-PAS monitors specify C2H2 ≤0.1 ppm; broadband-PAS products such as the Camlin TOTUS G9 also reach 0.1 ppm, while NDIR and online-GC products typically sit at ±0.5 ppm and 1 ppm respectively (vendor data). State your requirement explicitly, and pair it with the accuracy expression — most systems are specified as “absolute error + relative error” across a range that spans tens to thousands of ppm.
Environment, Communications, and Cybersecurity
An online DGA monitor lives outdoors on a transformer, so environmental adaptability is a hard requirement: an outdoor enclosure rating of IP55 and an operating range of −40 to +55 °C are typical for utility-grade equipment, plus electromagnetic compatibility for the substation environment. Communications should name the protocols and point tables — MODBUS RTU/TCP, IEC 61850 (MMS/GOOSE), IEC 60870-5-104, DNP3.0, RS485 — and treat analog 4–20 mA as backup only. Cybersecurity requirements should follow IEC 62443: encryption, access control, and data integrity, so the monitor behaves as a controlled device on the substation network rather than an open endpoint.
Three-Layer Acceptance
Acceptance should be “measurement as the criterion, evidence as the basis,” executed in three layers. The first layer is documentation: check the type-test report, third-party test report, metrological verification certificate, and factory test records to confirm specifications match the contract. The second layer is laboratory comparison: apply standard gas samples — for example C2H2 at two levels, one near the detection limit and one at a typical fault concentration — to verify each gas’s deviation, and run a comparison against offline laboratory gas chromatography to confirm online and offline data sit at the same order of uncertainty (laboratory analysis total uncertainty is on the order of ±15%). The third layer is site acceptance: verify installation and joint commissioning, communication-protocol integration, alarm and trending functions, store-and-forward of interrupted data, and the operability of calibration and maintenance procedures. Archive all records; they become the basis for warranty-period dispute resolution and subsequent periodic calibration.
PAS DGA for Online DGA Monitoring
When your RFQ reaches the evaluation stage, PAS DGA’s DGA-900 L-PAS monitor is specified against exactly these ten items: 9 gases plus moisture, C2H2 detection limit ≤0.1 ppm, consumable-free operation, IP55-rated enclosure for −40 to +55 °C, and MODBUS/IEC 61850/104/DNP3 integration. The underlying photoacoustic spectroscopy principle and our selection guidance give your team a documented basis for comparison. Contact PAS DGA for a specification sheet you can drop into your next RFQ.