How to inquire for an Oil-Immersed Transformer Procurement Parameter and Question Guide for supplier

2025-4-25 CTSS CTSS

How to inquire for an Oil-Immersed Transformer Procurement Parameter and Question Guide for suppliers

I. Key Parameters to Provide to the Supplier

1.       Rated Capacity

Unit: kVA or MVA (e.g., 500kVA, 10MVA).

2.       Voltage Ratings

Primary (HV) voltage (e.g., 10kV, 35kV);

Secondary (LV) voltage (e.g., 0.4kV, 6.6kV);

3.       Tap changer requirements (e.g., ±2×2.5%).

4.       Frequency

Typically 50Hz or 60Hz (region-dependent).

5.       Phase and Connection Group

Single-phase or three-phase;

6.       Vector group (e.g., Dyn11, Yyn0).

7.       Cooling Method

ONAN (Oil-Natural Air-Natural), ONAF (Oil-Natural Air-Forced), OFAF (Oil-Forced Air-Forced), etc.

1.       Insulation Level

Power frequency withstand voltage, lightning impulse withstand voltage (e.g., 70kV for 35kV class).

2.       Short-Circuit Impedance (Uk%)

Typically 4%~10% (must match grid requirements to limit fault current).

3.       Operating Environment

Indoor/outdoor installation;

Ambient temperature, altitude (e.g., derating required above 1000m).

4.       Efficiency Class

Standards (e.g., IEC 60076-20).

Special Requirements

5.       Enclosure protection (IP rating), anti-corrosion, moisture resistance, explosion-proofing;

6.       Accessories like temperature controls, Buchholz relay.

II. Questions to Ask the Supplier

1.       Technical Compliance

Does the transformer comply with international standards (e.g., IEC 60076)?

Are third-party test reports (e.g., type tests) available?

2.       Construction & Materials

1)       Core material (e.g., silicon steel grade: 30Q120, 27ZH100)?

2)       Winding conductor (copper or aluminum)?

3)       Tank type (corrugated, radiator-finned)?

4)       Losses & Efficiency

5)       No-load loss (P0) and load loss (Pk) values?

6)       Does it meet energy efficiency targets (e.g., Tier 1)?

3.       After-Sales Service

4.       Warranty period? Includes installation guidance.

5.       Emergency response time for repairs?

6.       Delivery & Installation

7.       Production lead time and delivery schedule?

8.       Transport dimensions/weight restrictions (e.g., door clearance, road weight limits)?

9.       Additional Details

1)       Is a neutral grounding device required?

2)       Brand preferences for accessories (oil level gauge, pressure relief valve)?