SMART (NM series) Buchholz relay with gas volume, oil temperature and oil moisture sensors
The SMART Buchholz Relay is a Buchholz relay with built-in sensors that keeps its protective functions and also passes data to the transformer monitoring system. Continuous measurement of gas volume, oil temperature and oil moisture shows a developing fault long before the protection operates and helps extend the service life of the transformer.
- Code 60
- capacitive gas volume sensor, 4–20 mA, 24 V DC supply
- Code 61
- Pt1000 temperature sensor, two-wire circuit
- Code 62
- oil moisture and temperature sensor; outputs 0–10 V, 0(4)–20 mA, RS-485 Modbus RTU
- Moisture
- water activity, relative saturation or absolute content
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The mechanical part works as in a standard relay. It responds to gas release, an oil surge and complete loss of insulating liquid, and gives alarm and trip signals. The basis is a double-float relay with characteristics to EN 50216-2 and IEC 60076-22-1, contacts rated 5–250 V and 0.01–6 A, IP56 enclosure and an operating temperature of −40…+55 °C. The sensor is built into the relay cover, while the electronic amplifier and processing unit sit in the cap of the terminal box.
The option with code 60 (NM series) has been produced since 2005 and adds a capacitive gas volume sensor. A standard relay signals gas only once a threshold volume is reached and does not show how fast the gas accumulates. Yet the dynamics say a lot about the fault. Powerful sudden damage produces a lot of gas in a short time, while low-energy faults release small volumes. The analogue sensor continuously measures the gas volume in the relay and outputs a 4–20 mA current signal. The 24 V DC supply is provided by the customer's system, which also processes the signal in the SCADA or monitoring system.
Option 61 adds a Pt1000 insulating liquid temperature sensor, connected in a two-wire circuit by screened cable to the customer's transducer. Option 62, offered since 2017, combines oil moisture and temperature sensors. Moisture is output as water activity, relative saturation or absolute content, and the temperature range is scalable. Together the two values immediately show whether there is a risk of free water forming. The sensor runs on 24 V DC and transmits data through 0–10 V or 0(4)–20 mA analogue signals or the digital RS-485 Modbus RTU interface, through which it is also parameterised.
SMART relays are installed on power transformers at substations, power plants and industrial facilities where remote condition monitoring is needed without separate analysers. For on-site gas analysis they are complemented by the ZG 1.2 gas sampling device and the BGT tester. The amplifier is connected with a four-core cable with an angled M12 connector; the manufacturer recommends taking the IP 67 cable from the delivery set. The pipe to the conservator is installed with a slope of 0° to 5°, as for a standard relay.
Technical specifications
| Code 60 | capacitive gas volume sensor, 4–20 mA, 24 V DC supply |
|---|---|
| Code 61 | Pt1000 temperature sensor, two-wire circuit |
| Code 62 | oil moisture and temperature sensor; outputs 0–10 V, 0(4)–20 mA, RS-485 Modbus RTU |
| Moisture | water activity, relative saturation or absolute content |
| Base relay | double-float Buchholz relay |
| Standards | EN 50216-2, IEC 60076-22-1 |
Request a price and lead time
SMART (NM series) Buchholz relay with gas volume, oil temperature and oil moisture sensors. 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 output signals does the gas volume sensor have?
The capacitive sensor with code 60 outputs an analogue 4–20 mA current signal. The 24 V DC supply is provided by the customer's system.
How is the oil moisture sensor data transmitted?
The sensor with code 62 has 0–10 V or 0(4)–20 mA analogue outputs and a digital RS-485 Modbus RTU interface. It is also parameterised through Modbus.
What standards does the base relay meet?
The SMART relay is based on a double-float Buchholz relay to EN 50216-2 and IEC 60076-22-1. The contacts are rated 5–250 V and 0.01–6 A, enclosure rating IP56.
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