Sfernice Resistor 47 Ohm 220W – RWST RB 30×250 Enameled
In high€‘power electronics, component quality dictates the service life of machinery. The Sfernice 47 Ohm 220W resistor, part of the rugged RWST series, is designed to withstand the harshest industrial environments, absorbing energy surges and dissipating heat efficiently and safely.
Detailed Technical Specifications:
Manufacturer: Sfernice (Now Vishay Intertechnology).
Series / Model: RWST RB 30×250 (Radial Band).
Component Type: Vitreous enamel wirewound power resistor
Nominal Resistance / Impedance: 47 Ohms („¦).
Power Rating (Dissipation): 220 Watts (W)
Tolerance: ±5% (Marked as K2).
Tube Dimensions: 249 mm length x 30 mm outer diameter (corresponds to the 30×250 standard).
Mounting: Includes metal clamps (RB collars) for direct mounting on panel or heatsink.
Coating: Green vitreous enamel. Provides hermetic sealing against moisture, corrosive environments, and superior dielectric insulation
Condition: New Old Stock (NOS). New piece from old inventory. Aesthetically, it looks very well preserved. Does not come with original box, but has been tested to guarantee continuity and ohmic accuracy.
The user wants a direct translation. I’ll provide it concisely.Industrial Applications of the Sfernice 47 Ohm 220W Resistor:
This resistor is intended for heavy-duty control panels, automation, and power electronics. Its main uses are:
Dynamic Braking for VFDs: Essential in variable frequency drives to absorb regenerative energy generated when stopping large three-phase motors.
Capacitor Discharge Systems (Bleeder Resistor): To safely discharge high-voltage capacitor banks when powering down a system.
Snubber and Limiting Circuits: Absorption of transient peaks and inrush current limiting in heavy machinery.
Brand History:
Sfernice was born in France as a cornerstone in the manufacturing of precision and power resistors for the military, aerospace, and European industrial markets. Its extremely high reputation for creating “indestructible” components (especially the enameled RWST series) led to the US corporation Vishay Intertechnology acquiring it in 1988, integrating its vitreous enamel technology into its global portfolio.
(FAQ)
Q: What does it mean that the resistor is from the RWST series?
A: The Sfernice/Vishay RWST series indicates it is a tubular wirewound resistor coated with high-temperature vitreous enamel. This means it is weather-sealed and exceptionally resistant to thermal shock and short-term overloads.
Q: Are the metal mounting brackets electrically isolated from the resistor?
A: Yes. The green vitreous enamel coating over the ceramic cylinder acts as a strong dielectric insulator, allowing the metal clamps (brackets) to be fastened directly to the chassis of your enclosure without causing a short circuit.
Q: Is it compatible as a replacement in modern equipment?
A: Absolutely. The laws of electricity do not change. If your variable frequency drive (VFD) or power circuit requires a 47 ohm, 220W (or lower) dissipation rating, this industrial component will surpass many lower-quality modern alternatives in durability.
