What is a single phase voltage monitoring relay and why do I need one?

A single phase voltage monitoring relay continuously measures the incoming voltage to your home or equipment and automatically disconnects the load if the voltage goes too high (overvoltage) or too low (undervoltage). In India, unstable grid voltage and neutral breaks are common causes of appliance and motor burnout. Installing a Novatek RN series relay protects your refrigerator, air conditioner, submersible pump, and other equipment by cutting power during dangerous voltage conditions and reconnecting only after stability is restored.

Which RN series relay should I choose — RN-119, RN-111M, or RN-113?

Choose the RN-119 if you have limited panel space and need a compact 1-DIN-module relay for loads up to 16A (3.6 kW) with digital precision programming. Choose the RN-111M if you prefer physical knobs for field adjustment and need a versatile relay for standard industrial panels. Choose the RN-113 if your load is heavy — up to 32A (7.2 kW) — because it can directly switch high-power appliances like large air conditioners or pump motors without needing a separate external contactor.

Can this relay protect my submersible pump from low voltage?

Yes. The RN series is widely used to protect submersible pump motors in homes, agriculture, and industrial setups. You set a minimum voltage threshold (Umin, adjustable down to 160V). If the incoming voltage falls below this — common during peak agricultural grid load — the relay disconnects the pump motor before it draws excessive current and burns out. The relay waits for voltage to return to normal and adds a programmable ON-delay (5 to 900 seconds) before reconnecting, allowing the pump's internal pressure to equalize.

What is neutral break protection and why is it critical in India?

A neutral break occurs when the neutral wire in a single-phase connection gets disconnected or becomes loose. In a three-phase distribution system supplying single-phase loads, a neutral break can cause the voltage in your single-phase line to spike to 415V instead of the normal 220-240V — instantly destroying connected appliances. The Novatek RN series detects this dangerous condition and trips immediately to disconnect your equipment. Many cheaper relays only monitor phase-to-neutral voltage and fail to respond correctly to a floating neutral, making neutral break protection a critical advantage of the RN series.

Can I use the RN-119 to protect my home air conditioner?

Yes, the RN-119 is an excellent choice for protecting air conditioners. It protects the AC compressor from overvoltage and undervoltage. Critically, its programmable ON-delay (5 to 900 seconds) prevents the compressor from restarting immediately after a power cut or voltage spike — ACs need time for refrigerant pressure to equalize before restarting, and rapid restarting without this delay is a common cause of compressor failure. The RN-119 handles this automatically.

What does True RMS measurement mean and why does it matter?

True RMS (Root Mean Square) is a precise method of measuring voltage that accounts for distorted waveforms caused by harmonics and electrical noise. Cheaper relays use 'average sensing', which can read an incorrect voltage during power quality events like surges or switching transients, causing false trips or — worse — missing real faults. The Novatek RN series uses True RMS measurement for accurate reading regardless of power quality, making it reliable in environments with variable loads, inverters, or heavy machinery on the same circuit.

How do I set the voltage thresholds on the RN-119?

The RN-119 uses a 3-digit LED display and push-buttons for programming. You set the minimum voltage threshold (Umin) between 160V and 220V, and the maximum voltage threshold (Umax) between 230V and 290V. You also set the reconnection delay (Ton) between 5 and 900 seconds. The display shows you the real-time incoming voltage at all times, so you can see exactly what the grid is delivering to your equipment.

Will the relay reconnect my appliances automatically after the power stabilises?

Yes. The RN series has auto-reset function. Once the voltage returns to within your set thresholds (between Umin and Umax), the relay starts counting down the ON-delay timer you have programmed. Once that timer expires, it automatically reconnects the load. You do not need to manually reset or restart anything — the protection is fully automatic.

Can the RN-113 handle a large load directly without a separate contactor?

Yes. The RN-113 has a built-in 32A relay contact, which can directly switch loads up to 7.2 kW. This is its key differentiator from the RN-119 and RN-111M (both rated 16A). For large air conditioners, industrial heaters, or heavy pump motors in this power range, the RN-113 can act as the switching element directly, simplifying your wiring and reducing installation cost compared to using a smaller relay with a separate magnetic contactor.

Where can I buy the Novatek RN series voltage relay in India?

You can purchase the complete RN series — RN-116, RN-101M, RN-111M, RN-113, RN-119 — directly from the Intelli-Electro online store at intelli-electro.com. Intelligent Electro Devices Pvt. Ltd. is the authorized retail partner and distributor of Novatek Electro India Pvt. Ltd. with pan-India shipping from their Delhi warehouse. You can also call +91-11-42143253 for purchasing assistance.

Single Phase Voltage & Neutral Monitoring Relays (RN series)

Novatek Electro India’s RN series—comprising the RN-119, RN-111M, and RN-113—is a line of microcontroller-based single-phase voltage monitoring relays. These devices are designed to protect domestic and industrial equipment from voltage fluctuations by disconnecting the load when parameters exceed safe limits and automatically re-energizing it once stability is restored.

How the RN Series Works

All three models function by continuously monitoring the True RMS (Root Mean Square) value of the input voltage. This ensures accuracy even if the electrical waveform is distorted by harmonics.

Sensing: The relay measures the incoming voltage in real-time.
Comparison: It compares the measured voltage against user-defined thresholds (Minimum U_{min} and Maximum U_{max}).
Tripping: If the voltage goes outside these bounds, the internal relay trips, opening the circuit to protect the load.
Auto-Reclosing: Once the voltage returns to the normal range, a programmable “ON-delay” timer begins counting down. The load is only reconnected after this timer expires, preventing damage from rapid power cycling (chattering).

Key Features and Comparison

While they share a core logic, each model is tailored for different power capacities and installation needs.

Feature	RN-119	RN-111M	RN-113
Max Current (Direct)	16 A (up to 3.6 kW)	16 A (up to 3.6 kW)	32 A (up to 7.2 kW)
Width on DIN Rail	18 mm (1 module)	35 mm (2 modules)	54 mm (3 modules)
Display	3-digit LED	3-digit LED	3-digit LED
Operating Modes	4 (Voltage, Min, Max, Delay)	4 (Voltage, Min, Max, Delay)	4 (Voltage, Min, Max, Delay)
Primary Use	Space-saving, low power	Industrial control panels	High-power appliances/Direct load

RN-119 (The Compact Version)

The RN-119 is ultra-compact, taking up only 18 mm of space. Despite its size, it offers a robust 16 A direct switching capacity. It is ideal for crowded electrical DBs where space is at a premium but high-accuracy protection is required. Digital Interface: Instead of using imprecise analog dials (potentiometers), it uses a 3-digit LED display and buttons for precise digital programming and real-time monitoring.

RN-111M (The Versatile Standard)

The RN-111M is the “classic” modular choice for industrial applications. It features four independent operation modes, allowing it to act as a simple time-delay relay or a dedicated under/over-voltage relay depending on how the front-panel toggle switches are set.

RN-113 (The High-Power Heavyweight)

The RN-113 is unique because it can directly handle loads up to 32 A. While other relays usually require an external magnetic contactor for heavy loads (like large ACs or pumps), the RN-113 can often handle these directly, simplifying the wiring and reducing the total cost of the protection system.

RN Series vs. Other Single-Phase Relays

Novatek’s RN series stands out from generic or analog voltage relays in several ways:

Neutral Break Protection: A critical advantage. The RN series can detect a “Neutral Break” (which can cause voltage to spike to 415V in a single-phase setup) and trip instantly to save your equipment. Many basic relays only monitor phase-to-neutral voltage and may fail to react correctly to a floating neutral.
True RMS Measurement: While cheaper relays use “average sensing” (which is inaccurate during power surges or noise), Novatek uses True RMS for precise measurement regardless of the power quality.
Digital Precision: Most standard relays use analog dials with vague markings. The RN series uses a Digital 3-digit LED display, showing the actual voltage in real-time and allowing for precise digital setting of thresholds.
Programmable AR Time: The re-energizing delay is adjustable from 5 to 900 seconds. This is vital for motor-based appliances (refrigerators, compressors) that need time for internal pressures to equalize before restarting.

RN-119: The Ultra-Compact Specialist

The RN-119 is the most modern and space-saving unit in the lineup. It is designed for applications where panel space is at a premium.

Form Factor: Occupies only 1 standard DIN module (the width of a single-pole MCB).
Operating Modes: Can be programmed to act as a full over/under voltage relay, just over-voltage, just under-voltage, or a simple ON-delay timer.
True RMS: Measures the True Root Mean Square value, ensuring accuracy even with distorted power waveforms.
Adjustable Delay: Features a programmable “ON delay” (5 to 900 seconds) to protect compressors (like in ACs or fridges) from rapid restarting.

RN-111M: The Standard Industrial Choice

The RN-111M is a versatile mid-sized relay that balances performance with traditional manual adjustments.

Visual Interface: Uses a 3-digit LED to show the current voltage, but settings are adjusted via physical knobs on the front, which many technicians find faster to set in the field.
Direct & Indirect Control: Can switch 16A directly; for higher loads, it is typically used to trigger the coil of a larger magnetic contactor.
Protection Speed: Features a “fast trip” for severe spikes (e.g., tripping in 0.12s if the voltage exceeds 30V above the set limit).

RN-113: The High-Power Workhorse

The RN-113 is designed for heavier loads that would typically require an external contactor for other relays.

High Current Rating: Its standout feature is the 32 A internal relay, allowing it to handle equipment up to 7 kW directly.
Four Operating Modes: Similar to the RN-111M, it can be set to different modes using toggle switches behind the front panel.
Comprehensive Monitoring: The display toggles between the actual voltage and the remaining time until the load is re-energized after a fault.

Common Features Across All Three

Auto-Reset: Automatically reconnects the load once the voltage returns to a safe range (after the user-defined time delay).
Neutral Break Protection: Critical for Indian power conditions, they disconnect the load if the neutral wire breaks (which can lead to 415V entering a single-phase appliance).
Wide Adjustment Range: * Umin: 160V – 220V
- Umax: 230V – 290V
- Time Delay (Ton): 5s – 900s