Distribution Transformer Testing: Routine, Type and Site Tests
Testing is the evidence that a transformer meets its specification. Knowing which tests exist, and which ones to ask for, lets you control quality before the unit reaches site.
This article explains the test categories and what each one proves.
Testing is the evidence that a transformer meets its specification. Knowing which tests exist, and which ones to ask for, lets you control quality before the unit reaches site.
This article explains the test categories and what each one proves.
Routine tests: every unit
Winding resistance. Confirms conductor integrity and correct connections
Voltage ratio and vector group. Confirms the turns ratio and winding configuration
Impedance voltage and load loss. Confirms the design impedance and copper losses
No-load loss and no-load current. Confirms core performance
Dielectric routine tests. Applied voltage and induced voltage withstand
Insulation resistance. Basic condition check
Functional checks. Tap changer, protection devices, monitoring, cooling
Type tests: one-off or per design
Lightning impulse test. Proves BIL capability against surges
Temperature rise test. Proves the cooling design at rated load
Short-circuit withstand test. Proves mechanical strength under fault
Sound level measurement. For projects with a noise limit
Factory acceptance testing (FAT)
FAT takes place at the manufacturer before dispatch, and the customer or an appointed inspector can witness it. Ask for the test programme in advance, then for certified reports afterwards.
Site acceptance testing (SAT)
On arrival and after installation, check for visual and transport damage, then test insulation resistance, ratio and vector group, protection and monitoring function, and earthing. Energise last, and monitor the load.
What to ask your supplier
Ask which routine tests are performed on every unit, which type test reports exist, whether you may witness testing, and what format and language the test documentation will use.
Frequently Asked Questions
Related Products, Applications and Support
Not sure which rating fits your project? Send us your load list and we will size it for you, or email info@xsdfftransformer.com, call +86 158 6789 7761 or WhatsApp +852 5416 2620.