Food, agri and cold chain: seasonal plants, year-round bills.

Your bill, line by line

Cold storage

A cold store pulls its heaviest load while it is being filled and the produce is cooled down. For the rest of the storage season the load is lighter and steady. If Contract Demand was set for the loading weeks, the bill keeps charging for it long after. Refrigeration compressors, condenser fans and evaporator fans make up most of the energy; a dirty condenser or frequent door openings show up as more kWh for the same stock.

• Monthly Maximum Demand against Contract Demand, to decide whether to revise it.
• Compressor energy per tonne stored, week by week.
• Night and off-peak running: cooling the store harder at night where the tariff rewards it.

Where a cold store’s energy goes

In a cold store, the refrigeration plant uses most of the energy. The rest goes to the fans, defrost, lights and pumps.

• Compressors do the work of moving heat out. They run hardest while fresh produce is pulled down to storage temperature.
• Condensers reject that heat outside. A dirty or crowded condenser makes every compressor work harder.
• Evaporator fans move cold air through the chambers, often around the clock.
• Defrost melts the ice that builds on evaporators, with heaters, hot gas or water.
• Lights, door heaters and pumps make up the rest.

Seven things that raise a cold store’s bill

1. A dirty condenser. Dust, leaves and blocked airflow raise the condensing temperature, and each degree adds a few percent to compressor energy.
2. Doors left open. Warm, damp air rushes in, adds heat and frosts the evaporators. Strip curtains, air curtains and quick-closing doors cut it.
3. Defrost set by the clock. Too often wastes heater energy and adds heat to the chamber. Too seldom leaves ice that blocks the air.
4. Damaged insulation. Wet or broken panels and gaps around doors let heat leak in all season.
5. Chambers colder than the produce needs. Every degree lower costs compressor energy for no benefit.
6. Compressors on part load. Several machines all running half-loaded use more energy than fewer machines running fully.
7. Everything starting at once. After a power cut, compressors and fans restarting together set the month’s Maximum Demand.

An example, for illustration: a dirty condenser

Say a store’s compressors use 3,000 kWh a day, and a fouled condenser raises that by 6%. That is 180 kWh a day, about 5,400 units a month. At ₹8 a unit, it costs about ₹43,000 a month, and nothing on the bill says why. Compressor energy per tonne in store, tracked every day, shows the rise within a week.

Illustrative figures, not from a real store. Your own savings depend on your plant, produce, climate and tariff.

A cold store energy checklist

• Every day: compressor kWh per tonne in store, and any chamber running far off its set point.
• Every week: clean condensers, check door seals and curtains, look for ice on evaporators.
• Every month: Maximum Demand against Contract Demand, peak-hour units, and power factor.
• End of the loading season: compare the peak with Contract Demand, and decide whether to revise it.

Dairy and milk chilling

Milk arrives in morning and evening collections, and chilling has to keep up straight away. Chillers, ice banks, pasteuriser pumps, homogenisers and cleaning pumps follow that rhythm. Building ice in off-peak hours and keeping collection peaks apart lowers both demand and peak-hour units.

• Demand during each collection, and whether chilling overlaps other large loads.
• Ice bank and chiller energy by hour of day.
• Energy per thousand litres handled.

Rice mills

Hullers, whiteners, polishers, colour sorters, elevators and dryer blowers run in a line. When paddy runs short or a batch changes, the line keeps turning empty. Over a season those empty hours are a large share of the bill.

• Running and idle time of the whole line and its largest motors.
• Energy per tonne of paddy, every day of the season.
• Power factor across the many motors, especially at part load.

Flour mills

Roller mills, plansifters, pneumatic conveying blowers and the cleaning section run together. Blowers and mills running with no feed, and unequal loading across roller mills, raise energy per tonne of wheat.

• Energy per tonne of wheat ground.
• Blower and mill motors on their own meters, with idle time.
• Demand when sections start after a stop.

Food processing and packaged foods

Ovens, fryers, blast freezers, cold rooms, packing lines and compressors share the supply. Freezing and baking cycles that start together set the month’s demand.

• Demand by line, so cycles can be staggered.
• Cold room and freezer energy on weekends and holidays.
• Energy per kg packed.

A worked example: Contract Demand after the season

A cold store with a 500 kVA Contract Demand reaches about 480 kVA while loading, then draws around 300 kVA for the rest of the year. On a tariff that bills at least 75% of Contract Demand, every quiet month is billed at 375 kVA, not 300. At ₹300 per kVA that is about ₹22,500 a month for demand the store does not use.

Tariff rules differ by state and category, and the figures are illustrative. A year of Maximum Demand history shows what your own Contract Demand should be. See Contract Demand.

Food and cold chain in KONDUKTOR® EMS

• Monthly Maximum Demand history against Contract Demand, with the date and time of each peak.
• Peak, normal and off-peak units per meter, with the saving from moving load to cheaper hours.
• Running, idle and stopped time for mill lines and compressors.
• Daily production entry, so energy per tonne is worked out every day.
• Supply interruptions recorded with their duration, and alerts on any reading crossing a limit you set.

Temperature sensors in chambers and cold rooms connect to the same RS-485 network, and automatic compressor scheduling through Modbus I/O cards is engineered for your store as part of your project.