500 kVA HT AVR Stabilises 33 kV Feeder for a Spinning Unit
1. Background & Setup
A large-scale cotton spinning mill near Solapur operating modern Rieter and LMW frame machines was experiencing frequent production breaks. The mill is supplied by a dedicated 33 kV high-tension overhead transmission line, which runs through rural zones susceptible to grid sags.
2. The Challenge & Downtime Costs
Fluctuations on the 33 kV utility line caused the mill's local step-down transformers (33kV to 415V) to deliver unstable LT supply. This caused frame motors to slip speed, breaking yarn and creating yarn defects. Installing separate stabilizers for every machine was cost-prohibitive and complicated to maintain.
3. Technical Diagnosis
Monitoring showed the 33 kV line fluctuated from 29 kV up to 36 kV during peak agricultural pump hours. Slow-response tap changers on the distribution line could not keep up with quick loads, leading to continuous voltage swings at the mill's service panel.
4. Active Transformer Solution
We installed a centralized 500 kVA High Tension Automatic Voltage Regulator (HT AVR) directly on the 33 kV utility inlet, upstream of all six distribution transformers. The HT AVR regulates voltage on the high-tension side, ensuring all secondary distribution buses receive a steady, balanced 415V LT feed.
Measured Outcomes
- Yarn breakage rate reduced by 87%, improving production quality.
- Replaced multiple small LT regulators with one centralized maintenance-free unit.
- Improved plant-wide motor efficiency, saving ₹11,40,000 in electricity costs annually.
- Eliminated thermal wear on downstream distribution transformers.
HT AVR (High Tension Automatic Voltage Regulator)
We design, test, and commission these systems to match unique industrial loads and environmental parameters.