Overload Relays & Power Controllers for Food Processing & Cold Chain

When Your Electricity Bill Is Bigger Than Your Refrigeration Bill

Here is a situation every panel-builder who has worked in food processing or cold chain infrastructure will recognise. The distribution company's maximum demand meter ticks past the sanctioned load at 6 PM — right when the blast freezers, compressors, conveyor motors and packaging lines are all running simultaneously. The discom records a maximum demand violation. A penalty clause triggers automatically. The billing cycle closes, and the facility pays for energy it could have managed differently, had the panel been smarter.

Demand-side management is not a new concept. What is new — and what this article is specifically about — is how modern overload relays and power controllers embedded inside the MCC or distribution panel can carry out load shedding of non-critical circuits, enforce current limits, monitor power factor, and protect motors, all without a SCADA system or a programmable controller. The OM-310, OM-163 and RMT-101 from Novatek Electro India are the panel-level building blocks that make this possible.

The Engineering Need: Why This Product Category Exists

Food processing and cold chain facilities share a specific electrical challenge: their load profile is non-linear and demand-intensive. Refrigeration compressors draw high starting currents. Blast freezers cycle on and off. CIP (clean-in-place) pump sets, packaging machines and conveyor drives all compete for capacity on the same feeder. The result is a jagged demand curve that repeatedly threatens the sanctioned maximum demand limit.

Traditional approaches — oversizing the transformer, negotiating a higher sanctioned load — are expensive and slow. The smarter approach is to manage demand at the panel level: detect when total load approaches a threshold, automatically shed non-critical loads (office HVAC, lighting feeders, auxiliary conveyors), and reconnect them when headroom is available. The relay or power controller that drives the contactor coil of each shedable circuit is the core execution element of this strategy.

Beyond demand management, these same devices protect the motors and heating elements they supervise from overcurrent, earth leakage, and voltage anomalies — reducing downtime in environments where an unexpected trip can mean product spoilage.

Features to Look for in a Power Controller or Overload Relay for Cold Chain and Food Processing

1. Current Range That Covers Your Load

A single-phase packaging line feeder might draw 20 A. A large ammonia compressor drive could pull 400 A. Confirm the relay's CT input range or direct-connect current range covers your load before selecting.

2. Power and Demand Monitoring Built In

A relay that only trips on overcurrent is only half useful. For demand management you need the device to also measure and display active power (kW), reactive power (kVAR), apparent power (kVA) and current — so the panel itself becomes a monitoring point.

3. Configurable Relay Output for Load Shedding

The relay output must be configurable to de-energise a contactor coil when a demand threshold is crossed, not just when a fault occurs. This is the distinction between a protection relay and a power controller.

4. Voltage Monitoring

Cold chain compressors are sensitive to voltage sag. An integrated voltage monitoring function that trips or alarms on under-voltage or over-voltage protects the compressor without requiring a separate voltage relay.

5. Earth Leakage Detection

In food processing environments — wet floors, wash-down areas, stainless steel structures — earth leakage is a genuine shock and fire risk. Look for a relay with residual-current or earth-fault detection.

6. Display and Diagnostics

A dual LED or multi-parameter digital display lets a technician read current, voltage, power and fault status directly at the panel, without a handheld meter or laptop.

The Three Models: OM-310, OM-163 and RMT-101

OM-310 — Demand Controller & Overcurrent / Earth Fault Relay

The OM-310 is a numeric, multi-functional protection relay designed for three-phase and four-wire distribution panels. It handles the full suite of functions a food processing or cold chain MCC needs: overcurrent protection, earth leakage protection, power monitoring, and active demand control — all in one DIN-rail device. The dual LED display shows real-time parameters and fault status simultaneously.

• Supply voltage: 380 – 415 V AC (three-phase)
• Current range: 5 A – 800 A (covering loads from 2.5 kW to 450 kW)
• Number of poles: 3-pole and 4-pole configurations
• Protection functions: Overcurrent, earth leakage, power monitoring, demand control
• Display: Dual LED display
• Price: Rs.15,687 per piece (ex-GST)

OM-163 — Single-Phase Power Controller, Current & Voltage Monitoring Relay

The OM-163 is the single-phase counterpart — a digital, automatic power controller and monitoring relay that measures total power (kVA), active power (kW), reactive power (kVAR), current consumption and mains voltage from a single device. It is powered directly from the circuit it monitors, eliminating the need for a separate control supply. Three display windows provide simultaneous readout. The relay output can enforce a configurable power limit, making it directly usable for single-phase load shedding and power factor observation.

• Supply voltage: 130 – 300 V AC (single-phase)
• Current rating: 63 A at 250 V AC
• Number of poles: 2-pole (single-phase)
• Measured parameters: Total power (0–14 kVA), active power (0–14 kW), reactive power (0–14 kVAR), current, voltage
• Controlled range: Total power 1–14 kVA, active power 1–14 kW, reactive power 1–14 kVAR
• Display: 3 × LED display windows
• Applications: Power limiting, voltage monitoring, energy metering, overcurrent relay
• Price: Rs.3,500 per piece (ex-GST)

RMT-101 — Overload Relay

The RMT-101 is a dedicated overload relay — the workhorse of motor protection and the essential output-side companion in any contactor-based load-shedding scheme. Where the OM-310 and OM-163 handle demand control and power monitoring at the feeder level, the RMT-101 provides the per-motor overload protection that keeps individual compressor and conveyor drive circuits from running into thermal damage during demand recovery cycles when loads reconnect.

• Price: Rs.5,475 per piece (ex-GST)
• Application: Motor overload protection, thermal protection of drives in panel-based load management schemes

Model Comparison Table

All prices ex-Delhi, ex-GST. GST @ 18% applicable extra. Prices as per Novatek Electro Price List 2026-27, effective 01.04.2026.

Quick Selection Guide

Application-Based Selection: If Your Installation Requires X, Choose Model Y

• If your installation requires three-phase demand control with earth fault protection on a feeder serving 2.5 kW to 450 kW loads — choose the OM-310. Its 5 A to 800 A current range covers everything from small condensing units to large screw compressor drives, and it integrates demand control with overcurrent and earth leakage protection in a single numeric relay.
• If your installation requires single-phase power limiting and energy monitoring on non-critical circuits you want to shed during peak demand — choose the OM-163. At Rs.3,500 it is one of the most cost-effective ways to add power monitoring and automatic load limiting to an existing single-phase circuit without rewiring.
• If your installation requires per-motor overload protection on every contactor in a load-shedding panel — specify the RMT-101 on each motor outgoing feeder. The OM-310 or OM-163 handles demand-level decisions at the incoming feeder; the RMT-101 protects each motor individually against thermal damage when it reconnects after a shedding cycle.
• If your installation requires both power monitoring and voltage monitoring on a wide voltage-range network (130–300 V) — the OM-163 is specifically designed for this, measuring and displaying voltage alongside kW, kVA and kVAR simultaneously.

Common Selection Mistakes to Avoid

Mistake 1: Using Only an Overload Relay for Demand Control

A conventional bimetal or electronic overload relay trips on motor overcurrent. It does not measure total feeder demand and cannot shed loads before a maximum demand violation occurs. Use the OM-310 or OM-163 for demand control at the incoming or sub-feeder level, and add the RMT-101 for per-motor protection on the outgoing circuits.

Mistake 2: Specifying OM-163 on a Three-Phase Feeder

The OM-163 is rated for single-phase (2-pole) applications up to 63 A at 250 V. For three-phase feeders — compressor MCCs, blast freezer distribution boards — the correct choice is the OM-310, which covers 380–415 V three-phase systems up to 800 A.

Mistake 3: Oversizing 'Just to Be Safe'

Selecting the OM-310 for a 10 A single-phase auxiliary circuit is wasteful and operationally incorrect. Use the OM-163 for single-phase feeders. Match the relay to the load type and phase configuration first, then check current range.

Mistake 4: Ignoring Earth Leakage Requirements in Wash-Down Zones

Food processing facilities operate in wet, wash-down environments. Only the OM-310 among these three models includes earth leakage protection. For any three-phase feeder in a wet process area, the OM-310's earth fault function is a critical selection criterion, not an optional extra.

Installation Tips from the Field

• CT sizing for OM-310: When connecting to feeders above 100 A, use appropriately rated current transformers. Verify CT secondary is rated for 5 A standard output to match relay input terminals.
• OM-163 supply wiring: The OM-163 is powered by the circuit it monitors — there is no separate control supply required. Confirm that the circuit voltage stays within the 130–300 V measurement range under all load and network conditions.
• Load shedding priority sequence: When using OM-310 or OM-163 for demand management, define a shedding hierarchy in the panel design: shed office HVAC and general lighting before auxiliary conveyors, and shed auxiliary conveyors before any refrigeration load. Never shed primary refrigeration in a cold chain application without temperature override logic.
• RMT-101 setting: Set the RMT-101 overload current to the motor nameplate full-load current (FLC). Do not uprate it to reduce nuisance tripping — if trips are frequent, investigate the mechanical load or starting cycle, not the relay setting.
• Panel ventilation: Numeric relays with LED displays generate low but non-zero heat. In compact MCCs, ensure adequate ventilation to maintain relay ambient below the rated operating temperature.

Why Novatek Electro?

• ISO 9001:2015 Certified: Quality management systems audited and certified — every relay leaving the factory is tested to documented acceptance criteria.
• CE Certified: Products meet European conformity requirements, relevant for export-oriented food processing OEMs and MNC-owned cold chain facilities operating to international standards.
• Made in India — Delhi-based Manufacturing: Shorter lead times, local spare availability and no import duty exposure compared with European or Asian imported relays.
• 30+ Years of Electrical Protection Device Manufacturing: Deep product knowledge and application engineering support across the full range of industrial protection relays.
• After-Sales Support: Technical support available through the distributor network and directly via Novatek Electro India — not a grey-market import with no local service path.

Frequently Asked Questions