Transformers
On-Load Tap Changer (OLTC) – Diverter Switch Assembly
A visual metaphor for electrical stress, controlled energy flow, and ever-changing grid dynamics
⚡ What This Equipment Does
The OLTC enables a power transformer to adjust its voltage while energized and carrying a load.
✔ No shutdown ❌
✔ No supply interruption ⚡
✔ Precise, smooth voltage regulation 🎯
🧩 Major Components (As Seen in the Assembly)
🟡 1. Insulating Oil / Composite Cylinder (Top Section)
- Yellowish cylindrical enclosure
- Constructed from oil-impregnated pressboard or epoxy
- Provides robust insulation against high-voltage stress ⚡
- Encloses the diverter switch
🧠 Acts as the primary defense against flashover and dielectric breakdown
⚙️ 2. Mechanical Drive & Flange Assembly
- Heavy-duty metallic flange secured with bolts 🔩
- Mounts the OLTC to the transformer tank
- Transmits motion from the Motor Drive Unit (MDU)
🔁 Allows automatic tap operations during voltage variations
🔄 3. Diverter Switch Mechanism (Middle Section)
- The functional heart ❤️ of the OLTC
- Executes make-before-break switching
- Employs transition resistors or reactors
⚠️ Prevents:
- Arcing damage 🔥
- Voltage dips 📉
- Sudden electrical transients ⚡
🔩 4. Tap Selector Contacts (Lower Section)
- Multiple discrete tap positions 🔢
- Copper contacts provide:
- Low contact resistance
- High current-carrying capability 💪
- Spring systems ensure firm contact pressure
📌 Determines the active transformer winding tap
🔌 5. Copper Conductors & Interconnections
- Clearly visible copper rods and links 🟠
- Safely carry high load currents
- Optimized design to reduce heating 🔥❌
🧠 System Perspective
The surrounding environment symbolically reflects the OLTC’s mission:
stabilizing voltage amid fluctuating and stressed grid conditions
⚡ Why OLTC Is Critical
✔ Maintains voltage stability
✔ Enhances overall power quality
✔ Safeguards consumer and industrial equipment
✔ Indispensable for:
- Long transmission networks
- Renewable energy integration 🌞🌬️
- Heavy industrial loads & VFD systems 🏭
🏭 Typical Applications
- 33/11 kV substations
- 132 / 220 / 400 kV power transformers
- GIS substations
- Solar and wind grid interconnections
