Single Phase Voltage Relays for Textile Commercial Loads — RN-111M & RN-113

Walk into the electrical room of any mid-sized textile manufacturing unit — the kind running a cluster of power looms, dyeing baths and finishing machines — and you will find something telling: a row of burnt MCB boxes, brown scorch marks on contactor terminals, and a maintenance log full of entries that read 'compressor failed — cause unknown.' The cause is almost never unknown to an experienced protection engineer. It is voltage. Specifically, it is the daily rhythm of under-voltage sags during peak production shifts and over-voltage spikes when heavy machinery trips off-load. These events do not announce themselves. They silently degrade insulation, stress capacitor banks, and eventually kill compressors, CCTV DVRs, POS systems and commercial air-conditioning units — the secondary but operationally critical loads that every textile facility depends on.

This article is about protecting those loads — not with expensive power conditioners or UPS banks — but with intelligent, adjustable single-phase voltage monitoring relays that interrupt supply before damage can occur.

The Power Quality Reality in Textile Manufacturing

Textile manufacturing is one of India's most energy-intensive industrial sectors. A typical composite mill or processing unit draws power simultaneously for spinning frames, weaving machines, dyeing vats, compressors and building services. This creates a continuously fluctuating load profile on the incoming supply. The consequences for single-phase commercial loads are predictable and severe.

What Actually Happens on the Factory Floor

• Under-voltage during peak production: When large three-phase motors start, line voltage on single-phase branches can sag to 170–185 V AC for several seconds. Cold storage compressors and commercial split ACs running in this range draw excess current, overheat motor windings and suffer premature bearing failure.
• Over-voltage during load shedding: When bulk loads trip simultaneously — a common occurrence during planned or unplanned interruptions — residual EMF and transformer tap mismatches can push single-phase voltage above 260–270 V AC. POS terminals, CCTV DVR power supplies and variable-speed fan drives are particularly vulnerable.
• Neutral integrity failures: In older textile facility wiring, neutral conductors are often undersized relative to phase conductors. A loose or broken neutral creates voltage asymmetry that subjects single-phase loads to unpredictable, damaging voltage levels.
• Repeated micro-interruptions: Process-related switching — contactors, solenoids, motorised valves — generates voltage transients that cumulatively stress the SMPS circuits inside CCTV cameras, access control panels and billing terminals.

Against this background, the engineering requirement is clear: every single-phase commercial load in a textile facility needs a dedicated voltage monitoring relay with adjustable trip thresholds, configurable time delays and a contact output capable of switching the load contactor or direct load connection.

Introducing the RN-111M and RN-113: Purpose-Built for Commercial Load Protection

Novatek Electro's RN-111M and RN-113 are DIN-rail mounted single-phase voltage monitoring relays designed for exactly this class of application. Both models monitor the incoming 220–240 V AC single-phase supply continuously and de-energise their output contact whenever voltage falls outside the configured window or a neutral break condition is detected.

RN-111M — 16 A Single Phase Voltage Monitoring Relay

At 16 A rated current with an SPDT output, the RN-111M is suited for directly switching smaller single-phase commercial loads — CCTV system distribution boards, POS terminal power strips and light commercial refrigeration units — where the load current stays within the relay's own contact rating.

RN-113 — 32 A Single Phase Voltage Monitoring Relay

The RN-113 steps up the contact rating to 32 A, making it the correct choice for driving contactors feeding commercial split ACs, small passenger or goods lifts, and walk-in cold storage units where compressor start currents demand a higher-rated switching path.

Why These Protection Features Matter in Textile Environments

Adjustable Voltage Window

Both relays allow the operator to set independent upper and lower voltage thresholds. In a textile facility where the utility supply can swing between 190 V and 265 V AC across a working day, being able to define a tight window — say 210 V to 250 V — means the relay trips before the load enters a damaging operating region, not after the damage is done.

Time Delay on Trip and Reconnect

Configurable time delays are not a convenience feature — they are an engineering necessity. A cold storage compressor cannot be restarted immediately after a fault clearance; the refrigerant needs time to equalise pressure across the compressor valves. A reconnect delay of 2–3 minutes prevents the compressor from attempting to restart against full head pressure, which would trigger the thermal overload and potentially cause valve damage. Similarly, a trip delay filters out momentary sags that would otherwise cause nuisance tripping of CCTV systems and POS terminals during heavy motor starts.

Neutral Break Detection

In older textile facility wiring, neutral breaks are a known failure mode. When the neutral is lost, single-phase loads can see voltages far above their rated levels depending on the load distribution on the three phases. Both the RN-111M and RN-113 include neutral break protection, which immediately opens the output contact under this condition — protecting connected equipment from an overvoltage event that a standard fuse or MCB would not catch in time.

SPDT Contact Output for Contactor Integration

The SPDT (1NO + 1NC) contact configuration allows both relays to be integrated into standard contactor control circuits. The NC contact can drive an alarm or indicator, while the NO contact feeds the contactor coil. This is particularly relevant for commercial ACs, cold storage systems and small lift motor control panels where contactor-based load switching is already the norm.

Application Mapping: Which Relay for Which Load

Cold Storage Units in Textile Warehousing

Walk-in cold rooms and chest freezers used for storing dye chemicals, adhesives or temperature-sensitive fabric finishes are compressor-driven loads highly sensitive to under-voltage. For cold storage applications with single-phase supply, the RN-113 (32 A) is recommended to handle the contactor switching for the compressor motor circuit, with the reconnect delay set to protect against short-cycle starts after voltage restoration.

CCTV Surveillance Systems

Textile manufacturing facilities typically run large CCTV networks covering production floors, warehouses and entry points. The DVR units, NVRs and PoE switches that form the backbone of these systems contain sensitive SMPS power supplies that are vulnerable to over-voltage. The RN-111M (16 A) is well-suited for protecting the distribution board feeding CCTV infrastructure, disconnecting supply during over-voltage events and reconnecting after a configurable delay.

POS and Billing Terminals

Factory outlet stores, fabric showrooms and canteen billing counters within textile complexes use POS terminals, barcode scanners and receipt printers — all SMPS-fed loads with tight voltage tolerances. The RN-111M provides cost-effective protection for these loads, with the upper trip threshold set to disconnect supply before the over-voltage reaches the terminal's power supply clamping voltage.

Commercial Split Air Conditioners

Office spaces, sample rooms and quality control laboratories within textile facilities are typically air-conditioned with commercial 1.5–2 tonne split units. These units draw 7–12 A at rated load, and their inverter drive boards are sensitive to both under-voltage and voltage transients. The RN-113 is recommended for AC circuits where the contactor and control wiring need to accommodate the compressor's starting current envelope.

Small Passenger and Goods Lifts

Single-phase small lifts — common in two- or three-floor textile office blocks and showrooms — present an interesting protection challenge. The lift control panel already includes a contactor; the RN-113's 32 A SPDT output can be wired into the lift controller's supply circuit to inhibit operation during under-voltage conditions that would cause the lift motor to stall or overheat.

Quick Selection Guide

Relevant Standards and Compliance References

Engineers specifying voltage monitoring relays for commercial and industrial applications in India should be aware of the following standards:

• IS 12360: Voltage bands for equipment operating on 230/400 V AC supply — defines the ±10% steady-state voltage tolerance that utility supplies are expected to maintain, and within which connected equipment must operate safely.
• IEC 60255-1: Measuring relays and protection equipment — general requirements, covering relay accuracy, response times and environmental performance.
• IEC 60947-5-1: Low-voltage switchgear and controlgear — control circuit devices and switching elements, applicable to the SPDT output contacts of monitoring relays used in contactor control circuits.
• IS 732 / IEC 60364: Electrical installations of buildings — relevant to wiring practices and protection coordination in commercial premises within textile facilities.
• Bureau of Energy Efficiency (BEE) guidelines for commercial ACs — specify minimum supply voltage requirements that map directly to the under-voltage trip thresholds configurable in both relays.

Why Novatek Electro?

• ISO 9001:2015 certified manufacturing: Every RN-111M and RN-113 unit is produced under a documented quality management system, ensuring consistent relay performance and contact reliability across production batches.
• CE certified: Both models carry CE marking, confirming compliance with relevant European directives for electrical safety and electromagnetic compatibility — a meaningful benchmark for product design discipline even in the Indian market.
• Made in India: Manufactured at Novatek Electro India Private Limited's facility in Delhi, with local supply chain accountability and faster spare availability through a national distributor network.
• 30+ years of protection relay expertise: Novatek Electro's parent organisation has over three decades of focused experience in electrical protection devices — this is not a diversified electronics company that incidentally makes relays.
• Accessible after-sales support: Technical queries are handled directly, with datasheet documentation, wiring diagrams and application guidance available through authorised channels — critical for panel builders and OEMs integrating these relays into custom panels.

Frequently Asked Questions