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Reliance 2SR21200

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Reliance 2SR21200
May 28, 2026

Reliance 2SR21200

The 2SR21200 is a snubber resistor unit (also called a surge/absorption resistor) from Reliance Electric, used for DC bus voltage suppression and braking energy dissipation in industrial drives (e.g., GP‑2000 series). It absorbs voltage spikes and regenerative energy during motor deceleration, protecting the drive’s power semiconductors. The unit is discontinued OEM; refurbished/used units are common for legacy system maintenance.

Description

Product Description

The 2SR21200 is a snubber resistor unit (also called a surge/absorption resistor) from Reliance Electric, used for DC bus voltage suppression and braking energy dissipation in industrial drives (e.g., GP‑2000 series). It absorbs voltage spikes and regenerative energy during motor deceleration, protecting the drive’s power semiconductors. The unit is discontinued OEM; refurbished/used units are common for legacy system maintenance.

Model Number Interpretation

  • 2: Series identifier (Reliance standard industrial accessory)

  • SR: Snubber Resistor (absorption/resistor unit)

  • 21200: 2 = 230 VAC class; 1200 = 1200 W power rating

Technical Specifications

  • Rated Power: 1200 W (continuous)

  • AC Input Voltage: 230 VAC (±10%), 1-phase, 50/60 Hz

  • DC Bus Voltage: 380 VDC (max)

  • Rated Current: 1 A (AC); 38 A (DC pulse)

  • Resistance Value: ~120 Ω (typical)

  • Enclosure: Steel cabinet, NEMA 1 (indoor, ventilated)

  • Cooling: Built‑in cooling fan (115/230 VAC)

  • Dimensions (H×W×D): approx. 450 × 300 × 250 mm

  • Weight: approx. 18–20 kg

  • Certifications: UL 508, CE (legacy)

  • Part Number Cross: D2‑3291 (Reliance internal part number)

Interface & Indicators

  • Power Terminals: L/N (230 VAC fan power); DC+ / DC− (drive DC bus connection)

  • Status LEDs:

    • Left: DC bus voltage (>50 VDC = ON)

    • Right: Braking current (active = ON)

  • Switched Output (S1): Dry contact for fault/alarm signaling

Core Functions

  • Voltage Spike Suppression: Absorbs transient overvoltage on the DC bus during motor braking

  • Regenerative Energy Dissipation: Converts excess motor energy into heat via the resistor

  • Drive Protection: Prevents overvoltage faults (OV) and damage to IGBTs/power modules

  • Fan‑Cooled Operation: Sustains 1200 W continuous power without overheating

  • Fault Indication: Visual LED status and dry contact for remote monitoring

Application Scenarios

  • Reliance GP‑2000 Series Drives: 230 VAC, 5–20 HP systems

  • General Industrial: Conveyors, cranes, mixers with frequent start/stop or rapid deceleration

  • Legacy Automation: Direct replacement for failed 2SR21200 units in existing 230 VAC drive systems

Usage & Maintenance

  • Installation: Mount vertically in a ventilated cabinet; allow 100 mm clearance for airflow

  • Wiring: Use 14 AWG (2.5 mm²) stranded copper for DC bus connections; torque terminals to 1.2 N·m

  • Power‑Up: Energize fan first (230 VAC), then connect DC bus

  • Maintenance: Quarterly—clean fan filter, check LED operation, verify terminal tightness

  • Safety: Disconnect AC and DC power; wait 5 minutes for capacitors to discharge before service


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