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NBL-W-RSS: What is a rain and snow sensor? Rain and snow sensor is a kind of instrument that utilizes the conductive property of rainwater and uses advanced detection circuit to detect whether there is rain or snow. What is the working principle of the rain and snow sensor?Rain Monitoring :The top of the rain and snow sensor uses grill electrodes to utilize the conductivity of water. When rain falls on the sensing area, the electrodes will be short-circuited so that the devic···
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Email:Arvin@niubol.com +Nearly 100 partner companies in more than 75 countries. We are committed to providing high-quality, practical products to meet your needs and help you solve problems. Our products comply with international standards and are certified with ISO, CE and RoHS.Product Details
The NiuBoL NBL-W-RSS Rain & Snow Sensor is a precipitation detection instrument designed to identify the presence or absence of rain and snow. It uses a surface grid electrode and an electronic detection circuit to identify moisture on the sensing surface, providing a switch signal for weather monitoring and automatic control systems.
The sensor incorporates an automatic heating function to reduce interference caused by accumulated snow, ice and residual moisture. A built-in processor evaluates the sensing signal and controls a relay output for connection to compatible controllers, weather station data loggers and alarm systems.
The NBL-W-RSS operates from DC 12–24V and provides a configurable normally open (NO) or normally closed (NC) switch output. It is suitable for meteorological stations, agriculture, roads, outdoor equipment protection, industrial monitoring and other applications requiring precipitation-presence detection.
| Parameter | Specification |
|---|---|
| Model | NBL-W-RSS |
| Product Name | Rain & Snow Sensor |
| Detection Parameter | Rain or snow presence / absence |
| Measurement Type | Qualitative precipitation detection |
| Sensing Principle | Surface grid electrode conductivity detection |
| Heating Function | Built-in automatic heating |
| Power Supply | DC 12–24V |
| Signal Output | Relay switch contact |
| Output Configuration | Normally Open (NO) / Normally Closed (NC) options |
| Contact Capacity | 5A, 250VAC / 30VDC |
| Power Consumption | 1.5W |
| Operating Temperature | -40 to 80°C |
| Operating Humidity | ≤100% RH |
| Standard Cable Length | 5 m |
| Cable Voltage Rating | 300V |
| Product Weight | Approximately 120 g |
| Recommended Installation Angle | Approximately 15° from horizontal |
The relay contact capacity and cable voltage rating are electrical specifications. They do not represent the sensor's power supply voltage. The sensing device requires DC 12–24V power.
The NBL-W-RSS uses conductive grid electrodes arranged on the upper sensing surface. Under dry conditions, the electrical characteristics between the electrodes differ from those observed when conductive water is present.
When raindrops or melted snow contact the electrode surface, the electrical conductivity between the electrodes changes. The detection circuit processes this signal to determine the presence of moisture associated with precipitation.
The sensor then changes the state of its relay contact according to the configured output logic. A connected data logger, PLC or monitoring controller can use this signal to record a precipitation event, activate a warning or initiate an appropriate control function.
| Stage | Operation |
|---|---|
| 1. Precipitation Contact | Rain or snow reaches the exposed electrode surface. |
| 2. Conductivity Change | Water or melted snow changes the electrical response between the grid electrodes. |
| 3. Signal Processing | The electronic circuit evaluates the detected moisture condition. |
| 4. Relay Switching | The relay contact changes state according to the output configuration. |
| 5. Monitoring or Control | The connected controller records the event or performs a programmed action. |
Snow and ice can accumulate on an exposed sensing surface, particularly during extended periods of low temperature. The NBL-W-RSS incorporates an automatic heating function that helps melt snow or ice in contact with the electrodes and reduces interference caused by persistent frozen deposits.
Heating allows precipitation in the form of snow to produce detectable moisture on the electrode surface. It also assists the sensing area in returning toward a dry condition after precipitation ends.
The heating function supports precipitation-presence detection. It does not measure snow accumulation, snowfall intensity or snow depth.
A rain and snow detection sensor and a rainfall measuring instrument perform different functions. The NBL-W-RSS is intended to provide a qualitative indication of precipitation-related moisture. It does not generate numerical rainfall totals.
| Instrument | Measured Parameter | Typical Output |
|---|---|---|
| Rain & Snow Sensor | Precipitation presence / absence | Relay switch status |
| Tipping Bucket Rain Gauge | Liquid rainfall accumulation and calculated intensity | Rainfall in mm / mm/h |
| Snow Depth Sensor | Accumulated snow depth | Snow depth in mm or cm |
For applications requiring both precipitation detection and quantitative rainfall measurement, the NBL-W-RSS can be combined with an appropriate rain gauge. Snow depth monitoring requires a separate snow depth instrument.
Rain and Snow Detection
Detects precipitation-related moisture on the electrode surface.
Automatic Heating
Helps melt deposited snow or ice and reduce sensing-surface interference.
Relay Contact Output
Provides a switch signal for integration with compatible controllers.
NO / NC Options
Output contact logic can be selected according to project requirements.
DC 12–24V Supply
Suitable for integration into industrial and meteorological DC systems.
Compact Structure
Approximately 120 g with a standard 5 m cable.
The NBL-W-RSS requires a DC power supply for the internal detection circuit and heating function. Its relay contact provides a separate switching signal to the connected monitoring or control equipment.
| Wire Color | Function |
|---|---|
| Red | DC Power Positive (+) |
| Blue | DC Power Negative (-) |
| Black | Relay Contact Wire 1 |
| Yellow | Relay Contact Wire 2 |
The black and yellow wires form the switching contact pair and are not polarity-sensitive. The receiving controller should provide a compatible digital input or switch-sensing circuit.
Important: The relay contact is a switching interface, not an independent power supply for external equipment. When controlling a load that requires electrical power, use a correctly rated external supply and suitable switching circuit. Inductive loads such as motors and solenoids may require additional protection or an external contactor.
| Output Type | Contact Arrangement |
|---|---|
| Normally Open (NO) | The contact is open in its normal reference state and closes when the relay activates. |
| Normally Closed (NC) | The contact is closed in its normal reference state and opens when the relay activates. |
The required NO or NC output option should be specified when ordering. The relationship between precipitation detection and relay activation should be confirmed during system commissioning.
The sensor should be installed in an outdoor position where rainfall and snowfall can reach the sensing surface naturally. The recommended mounting angle is approximately 15° relative to the horizontal plane, helping reduce the accumulation of water and snow.
| Installation Item | Recommendation |
|---|---|
| Monitoring Location | Choose an exposed location representative of the monitored outdoor environment. |
| Sensing Surface | Keep the electrode surface unobstructed so precipitation can reach it. |
| Mounting Angle | Approximately 15° from horizontal |
| Mounting Hardware | Use the mounting holes and four M3 × 35 mm screws with suitable nuts and support hardware. |
| Power Supply | Connect a suitable DC 12–24V supply with the correct polarity. |
| Relay Wiring | Connect the switch contact pair to a compatible controller input. |
| Surface Protection | Avoid contact with sharp tools, corrosive liquids or materials that could damage the sensing electrodes. |
| Commissioning | Verify the dry and wet switching states before connecting the signal to automatic equipment control logic. |
| Application | Typical Use |
|---|---|
| Automatic Weather Stations | Provide a rain/snow presence signal as part of an environmental observation system. |
| Roads and Bridges | Provide precipitation-condition input for traffic monitoring and warning controllers. |
| Agricultural Greenhouses | Supply a precipitation detection signal for roof, vent or window control systems. |
| Industrial Equipment | Support weather-dependent control of suitable outdoor machinery or protective covers. |
| Solar Energy Installations | Provide precipitation-presence information to compatible PV monitoring or equipment protection systems. |
| Ports and Coastal Facilities | Provide rain/snow condition signals for local environmental monitoring equipment. |
| Outdoor Displays | Trigger compatible protective or operational responses during precipitation events. |
| Research and Laboratories | Detect precipitation-related wetting events for experimental or monitoring purposes. |
The NBL-W-RSS can be integrated with a PLC, data logger or industrial controller equipped with a compatible switch input. The connected system detects a relay status change and processes the result according to its configured logic.
NBL-W-RSS Sensor → Relay Contact Input → PLC / Data Logger → Monitoring or Control System
| System Component | Function |
|---|---|
| NBL-W-RSS Rain & Snow Sensor | Detects precipitation-related moisture and changes its relay status. |
| DC Power Supply | Provides DC 12–24V power to the sensor. |
| PLC / Data Logger | Reads the relay contact status through a compatible input. |
| Control Relay / Contactor | Optionally switches external equipment when commanded by the controller. |
| Gateway / Monitoring Platform | Optionally records and transmits precipitation event status. |
For example, a greenhouse controller can use a rain detection signal as one input to a roof-closing sequence. The controller should also consider motor protection, position feedback, manual overrides and other required safety conditions.
The standard NBL-W-RSS output is a relay switch contact. Direct RS485 Modbus communication is not part of the standard output specification.
Periodic inspection helps maintain reliable rain and snow detection. The electrode surface should remain clean and free from accumulated dirt or material that could create unwanted conductive paths.
| Condition | Recommended Check |
|---|---|
| No Detection Output | Check DC power, cable connections, relay wiring and the receiving controller's input configuration. |
| Unexpected Wet Status | Inspect the electrode surface for retained water, dirt, deposits or conductive contamination. |
| Snow Detection Problems | Check the sensor power supply, heating operation and accumulation of snow or ice on the surface. |
| Incorrect Controller Status | Verify whether the connected input expects normally open or normally closed contact behavior. |
| Intermittent Switching | Check loose connections, surface contamination and changing wet/dry conditions. |
| Physical Damage | Inspect the sensing surface, cable and mounting hardware. Avoid disassembling the sensor housing. |
A1. It detects precipitation-related moisture on the sensing surface and provides a qualitative rain/snow presence or absence signal.
A2. No. It does not measure rainfall accumulation or rainfall intensity. A rain gauge is required for quantitative rainfall measurement.
A3. The standard sensor provides precipitation-presence detection rather than separate quantitative or classified rain and snow outputs. Additional meteorological measurements may be needed to distinguish precipitation types.
A4. Heating helps melt snow and ice on the electrode surface, allowing conductive moisture to be detected and reducing persistent accumulation.
A5. The standard output is a relay switch contact, not RS485 Modbus. It can connect to compatible digital or switch inputs on a controller or data logger.
A6. The specified supply is DC 12–24V, with 1.5W product power consumption.
A7. No. The switching contact does not independently supply power to connected loads. External equipment must be powered and switched through an appropriate circuit.
A8. Install the sensing surface at approximately 15° from horizontal to help prevent excessive rainwater and snow accumulation.
A9. Yes. Its relay status can be used as an input to a compatible controller that operates windows, roof covers or other equipment according to suitable control and safety logic.
NBL-W-RSS-Rain-Snow-Sensor-instruction-manual.pdf
The NiuBoL NBL-W-RSS Rain & Snow Sensor provides a practical precipitation-presence detection solution for automatic weather stations, outdoor equipment, greenhouse controllers, industrial facilities and transportation monitoring systems.
With conductive grid electrodes, automatic heating, DC 12–24V supply and normally open or normally closed relay output options, the sensor can be integrated into systems requiring a simple rain/snow detection signal.
For quotation and configuration, specify the required quantity, operating voltage, relay contact configuration, installation environment and receiving controller input type.
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