EMR Tap Changers Private Limited

Oil-free, dry-type on-load tap-changer (OLTC) for voltage regulation in dry-type transformers.

Single-phase modular unit directly mounted on the transformer limb.

Arc-free switching using vacuum interrupters and mechanical actuation via motor drive.

Modular and scalable configuration: Single-pole, three-pole delta, or star arrangements.

Easy integration with dedicated tap-changer modules per transformer limb.

High Current & Voltage Handling:

• Rated through-current: 500 A

• Max. step voltage: 900 V (linear insulation)

• Supports up to 17 tap positions

• Suitable for indoor use up to 36 kV and higher power applications

Compact Design:

• Integrated tap selector and diverter switch with high-speed resistor-type system

• Space-efficient construction

Reliable Operation:

• Movable tap contacts and diverter driven by spring-energy actuator and servo motor

• Ensures consistent, high-speed, and safe switching

Vacuum Interrupters:

• Proven vacuum technology for arc-free load switching

• Low maintenance and long service life

Motorized Drive Control:

• Step-by-step switching with motor drive

• Mechanically linked to OLTC for precise tap control

User-Friendly Operation:

• Clear electrical and mechanical position indicators

• Suitable for both remote and local control

Rugged Protection:

• Enclosed motor drive suitable for outdoor use

• For dry-type transformers, motor can be encapsulated inside transformer tank

Number of Poles: 1 or 3

Max. Rated Through-Current (IL): 500 A

Rated Short-Time Withstand Current (r.m.s.): 12.5 kA

Rated Short-Circuit Duration: 3 seconds

Rated Peak Withstand Current: 12.5 kA

Max. Rated Step Voltage (Uₛ): 900 V

Step Capacity: 250 kVA

Operating Positions: 9

Rated Frequency: 50 / 60 Hz

Highest Equipment Voltage (Um): 36 kV

Lightning Impulse Voltage (to ground & between phases): 200 kV

AC Withstand Voltage (1 min, to ground & between phases): 85 kV

Lightning Impulse Voltage (between adjacent tap contacts): 20 kV

AC Withstand Voltage (1 min, between adjacent contacts): 9 kV

Lightning Impulse Voltage (between first & last contacts): 80 kV

AC Withstand Voltage (1 min, between first & last contacts): 20 kV

Installation Position: Vertical, flange on top

Ambient Temperature Range: -25°C to +65°C

Protection Design: Outdoor-capable housing

Features:

• Step-by-step operation (local and remote)

• Electrical & mechanical position indication

• Remote position feedback connectivity