Single-float Buchholz gas relay DN25 for transformers up to 1600 kVA
EMB single-float Buchholz relays protect small oil-immersed transformers with an oil conservator and arc suppression reactors, and also monitor oil-filled bushings and cable terminations. All types in the range have a nominal bore of DN 25 and are designed for transformers rated up to 1600 kVA. The relays comply with EN 50216-2 and IEC 60076-22-1.
- Types
- 01 (AG 25, thread G 1½″), 02 (AF 25/6), 03 (AF 25/10), 25 (AF 25), 30 (AF 25/10 G)
- Nominal bore
- DN 25
- Protected transformer rating
- ≤ 1600 kVA
- Contacts
- AC/DC 5–250 V, 0.01–6 A; AC 1500 VA / DC 1250 W
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The relay is installed in the pipe between the tank of the protected unit and the oil conservator. In normal operation the housing is completely filled with insulating liquid and the float is at the top. The upper and lower systems are functionally combined here, and this is the main difference from double-float relays. Gas accumulation, oil loss or a liquid flow surge all result in a command to trip the transformer immediately. This arrangement suits small units where a separate alarm stage is not required.
The flap is held by a permanent magnet. It operates in less than 0.1 s when the flow velocity exceeds the setting of 0.65–3.00 m/s (tolerance ±15 %). On gas, the relay responds to an accumulation of 200–300 cm³, and the gas volume is visible in the inspection windows with a scale. The cover carries an air vent valve, a test button and a terminal box with magnetically operated contacts (reed switches). A gas sample for analysis is taken through the valve.
The range includes type 01 with a G 1½″ threaded connection and flanged types 02, 03, 25 and 30, including versions with a plain flange. The weight depends on the type and is 3.1–4.0 kg. The housing and cover are cast from weather-resistant aluminium alloy with a two-component coating, the degree of protection is IP56, and the relay is suitable for outdoor and indoor installation. It works with all common insulating liquids. The lightest in the range, threaded type 01, weighs 3.1 kg, flanged types 03 and 30 weigh 4.0 kg each.
The contacts switch AC/DC 5–250 V at a current of 0.01–6 A, the switching capacity is 1500 VA AC and 1250 W DC, and the insulation dielectric strength is 2500 V. The ambient temperature range is −40…+55 °C, oil −40…+115 °C. The relay withstands vibration of 2–200 Hz/2 g and shock of 25 g (class 4M6), pressure of 0.25 MPa and vacuum, and does not respond to magnetic fields up to 25 mT. Each unit undergoes dielectric strength, leak tightness, functional and flow tests. The delivery includes a test report and instructions in the agreed language.
Technical specifications
| Types | 01 (AG 25, thread G 1½″), 02 (AF 25/6), 03 (AF 25/10), 25 (AF 25), 30 (AF 25/10 G) |
|---|---|
| Nominal bore | DN 25 |
| Protected transformer rating | ≤ 1600 kVA |
| Contacts | AC/DC 5–250 V, 0.01–6 A; AC 1500 VA / DC 1250 W |
| Dielectric strength | AC 2500 V |
| Ambient temperature | −40…+55 °C |
| Liquid temperature | −40…+115 °C (up to +135 °C — var. 21) |
| Gas operation | 200–300 cm³ |
| Flow operation | 0.65–3.00 m/s ±15 % |
| Degree of protection | IP56 |
| Weight | 3.1–4.0 kg |
| Standards | EN 50216-2, IEC 60076-22-1 |
Replacement for
transformer protection relay РЗТ-25 (DN25 gas relay for transformers up to 1600 kVA)
selected by purpose and main parameters, please confirm with our manager
Request a price and lead time
Single-float Buchholz gas relay DN25 for transformers up to 1600 kVA. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8536 49 00 00 |
|---|---|
| HS, 6 digits | 8536 49 |
| CN (EU) | 8536 49 00 |
| HTSUS (USA) | 8536 49 00 85 |
| China customs tariff | 8536 49 00 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
What transformer rating is the single-float relay designed for?
All types in the range (01, 02, 03, 25, 30) for DN 25 are designed for transformers up to 1600 kVA. The relay weighs 3.1–4.0 kg.
How does a single-float relay differ from a double-float relay?
The upper and lower systems of a single-float relay are functionally combined. Gas, oil loss or a flow surge give a command to trip the transformer immediately.
What can replace the РЗТ-25 relay on a transformer up to 1600 kVA?
The EMB single-float DN 25 relay performs gas protection of small transformers. The connection type is selected according to the existing pipe and the application; agree the final choice with the manager.
Other analogues
European analogues of РЗТ-25 from other manufacturers and series.
Oil-filled equipment on ukrsk.com.ua (Ukrainian pages): Setavolt iSA — industrial three-phase induction variable transformers · IVR / IVRI — three-phase oil-filled induction voltage stabilizer
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