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R.C. Snubber

Product Overview & Application

SNUBBER open FrontR.C. snubbers are a passive electrical devices, comprised of appropriately selected resistors and capacitors, which are used for protecting medium voltage power transformers from electrical switching transients. While lightning arresters help protect the transformers from the high voltage spikes that appear on the line after a lightning strike, snubbers are better suited for the more common problem of circuit breaker switching transients. Examples of the switching operation include instances where a circuit breaker switches between transformer primaries, or automatically triggered switching between grid and reserve power.

When a circuit breaker interrupts current flow, an arc develops across its contacts. The rapid current interruption usually occurs somewhere other than the current zero-crossing point, giving rise to a Transient Recovery Voltage (TRV), which has significant high-frequency content. If the transients are at the natural resonance frequency of the system, then there is a possibility of internal oscillatory voltages developing in the primary windings of the transformer. A high turn-to-turn voltage will result, which will lead to damage of the insulation.

The problem is further exasperated with modern vacuum-type circuit breakers, which have shorter distances between contacts. This serves to increase the speed of the interrupting cycle. The transient level and frequency are functions of the physical distance between the breaker and transformer, transformer construction, the type of load being switched, and the switching characteristic of the breaker.

The RC-snubber network lowers the frequency of the transient voltage applied to the transformer primary below the resonance frequency of the circuit. It reduces the development of the oscillatory voltages and provides a low impedance path to ground for the transients.

Snubbers are a low cost means for protecting a transformer against a costly repair and related downtime. In designing medium voltage power systems, it is a good practice to at least leave space for future installation of a snubber network.

Product Specification

Voltage Class  2.4kV to 34.5kV (150kV BIL)
Frequency  60Hz (50/60Hz Optional)
Fuse  6A Full Range Current Limiting Fuse
Resistor  20 - 50 Ohm (+/- 10%) Tubular Non-Inductive Resistor
Capacitor  0.13uF, 0.25uF, 0.5uF Surge Capacitor
Enclosure Type  Type 1 Indoor
Enclosure Finish  ANSI/ASA 61 Grey
Mounting  Floor Mounting
Warranty  12 Months (See Warranty and Limitations)
Quality System  ISO 9001:2015 Quality Management System
Optional Features & Accessories
  • Snubber Ground Current Monitoring Circuits
  • Distribution, Intermediate or Station Class Surge Arresters
  • Voltage Indicators / Glow Tubes
  • Type 1, 3R or 4X Enclsoure
  • 304 & 316L Stainless Steel Enclosure
  • Custom Enclosure Finish (Color)