Why Is Your Dry Type Transformer Overheating?

Since transformers convert high voltages into consumable power, they generate significant heat. This heat can significantly affect the transformer's efficiency and will shorten its life span. With energy efficiency becoming a top priority in many of today's power applications, choosing a dry type unit that can adequately meet the required power needs and subsequent thermal loads for your specific application is crucial.

 

Dry type transformers rely on circulating air and other internal components like insulation and windings to prevent the transformer from overheating. Overheating occurs when the transformer generates more heat than anticipated - sometimes due to higher loads - dissipates it slower than expected - such as in cases with insufficient airflow - or some combination of the two. Without the proper cooling measures or when used for the wrong application, any transformer design can overheat, become unsafe and eventually combust.

 

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What Causes a Dry Type Transformer to Overheat?

While many dry type transformer designs can last several decades, constant exposure to heat above a unit's limit will significantly decrease its service life. Low-quality transformers with substandard insulation and windings often generate more heat, leading to an increased temperature rise, also called C-rise.

 

The average temperature increase of a unit over the ambient temperature when the transformer is fully loaded determines the C-rise. The better a transformer's performance and efficiency, the lower the C-rise.

 

Several factors that can cause a transformer to overheat or increase its C-rise include:

• Improper load rating selection: Selecting a transformer with a rating that can handle the intended application is crucial. The load rating is the maximum power a unit can efficiently and safely handle without causing damage or overheating.
• Inadequate airflow: Installing a dry type unit in a location with sufficient airflow and ventilation is vital. Even if a transformer is in an enclosure with air vents, it should not be near anything obstructing the airflow.
• Poor Insulation: Various insulation types transfer or dissipate heat at different rates. ELSCO uses DuPont Nomex^® Type 410 insulation because it offers effective protection against temperature failure.
• Low-quality windings: Prolonged temperatures exceeding the design temperature can break down the windings' dielectric strength, leading to power surges, hot spots or total system failure. Different winding methods can also help improve a transformer's C-rise.

 

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Product Parameters

Rated Capacity (KVA)	Junction group labe	Voltage combination(KV)			No-load current (%)	Load loss (W)	No-load loss (W)	Short circuit impedance (%)
		(H.V.)	High voltage tap range(%)	(L.V.)
30	Dyn11 YynQ	10 6.3 6	±5 ±2×2.5% or -1 ×2.5% +3	0.4	2.00	710	150	4.0
50					2.00	1000	215
80					1.50	1380	295
100					1.50	1570	320
125					1.30	1850	375
160					1.30	2130	430
200					1.10	2530	495
250					1.10	2760	575
315					1.00	3470	705
400					1.00	3990	785
500					1.00	4880	930
630					0.85	5880	1070
630					0.85	5960	1040	6.0
800					0.85	6960	1210
100C					0.85	8130	1410
1250					0.85	9690	1670
1600					0.85	11730	1960
2000					0.70	14450	2440
2500					0.70	17170	2880