NEPSI

The Most Trusted Name in Power Factor Correction and Harmonic Filtering

TRANSFORMER SURGE PROTECTION - RC SNUBBERS


NEPSI's RC Snubbers protect medium-voltage transformer primary windings from high frequency voltage transients.

Key applications requiring RC Snubber protection include:

  1. Medium voltage transformers switched with primary side vacuum or SF6 circuit breakers.
  2. Transformers that are fed with short feeder cables or short bus duct runs.
  3. Dry-type and cast-coil-type transformers and some liquid-filled transformers.

Figure 1 - NEPSI's RC Snubbers protect from high frequency voltage transiets.

PRODUCT SCOPE

  1. Operating Voltage: 2.4kV through 34.5kV (38kV Max)
  2. Impulse Withstand Voltage: 60kV BIL - 200kV BIL
  3. Surge Capacitance Rating (μF): 0.125, 0.25, 0.5, 1, or as specified
  4. Surge Resistance Rating: 30 Ohms to 200 Ohms, 1kW/Phase
  5. Phase-to-Phase and Phase-to-Ground MOV’s (lightning arresters) rated for your application to 48kV Duty Rating; Heavy Duty Distribution Class or Station Class

  1. Integral protection, control, and monitoring systems
  2. Integral air-disconnect /ground switch
  3. Metal-Enclosed Design: NEMA 1, 3R, 4X, 12 | IEC IP10, IP14, IP56, IP52
  4. Comes fully assembled, tested, and ready for interconnection
BENEFITS

  1. Protect against inter-turn insulation failure
  2. Extend transformer life
  3. Reduce the likelihood of circuit breaker pre-strike, re-strike, and re-ignition

  1. Reduce the magnitude and rate-of-rise of voltage transients
  2. Dampen resonant transients
  3. Reduce production downtime due to insulation failures
  4. Easy installation



HOW TO ORDER

RC Snubbers manufactured by NEPSI are custom built to meet your requirements.

In general, they are composed of a combination of a capacitor and a resistor (as shown in the figures below) to reduce the magnitude and frequency of a transformer transient terminal voltage. Fuses are often applied for short circuit protection and to disconnect the RC Snubber should it fail.

Resistance value are most often rated 30 ohms as this value of resistance is suitable for virtually all installations.

Lightning arresters, if not included in the transformer terminal box, are provided to limit the magnitude or peak voltage associated with phase-to-phase and phase-to-ground transients. These are rated based on system grounding.

Other supporting equipment, such as an air- disconnect switch, current loss detection, and blown fuse detection are also available with our systems.

Contact the factory or your nearest sales representative for options and voltages not shown.

PART NUMBER CREATION




For example, an RC Snubber for a 24.9kV three-wire solidly ground system requiring Phase-to-Phase and Phase-to-Ground Lightning arresters, blown fuse detection would have a part number of: RC-D-24.9-YG-PGF




RC SNUBBER - DIRECT CONNECTION




RC SNUBBER - WITH OPTIONAL DISCONNECT SWITCH



GUIDE FORM SPECIFICATIONS

Guide Form Specification for RC Snubbers

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