Epoxy Products
Resistive Capacitive Voltage Sensor
More than 15 years of experience in medium voltage sensors
The resistive-capacitive voltage sensor (RCVS) combines both divider principles in one cast epoxy part, to give an accurate and reliable image of the voltage on the high voltage line. Accuracy classes run from 1% down to 0.2%, for 17, 24, 36, 52 and 72 kV medium voltage networks.
The hybrid exists because the two principles fall short in different places. A purely resistive divider is accurate but dissipates; a purely capacitive one is compact but its behaviour is tied to frequency. Combining them gives a part that operates reliably across a wide frequency range while staying small enough to sit inside a switchgear panel.
Unlike conventional instrument transformers, RCVS units contain no saturable cores. They therefore cannot fall into ferroresonance, which removes a failure mode rather than damping it — and for anyone who has had to engineer that condition out of a distribution panel, this is usually the argument that settles the choice.
The result is a sensor suited both to measuring network conditions and to determining where a fault came from: precise across frequency, stable, and compact enough to retrofit.
Send us the network voltage, the accuracy class and the space available. Custom dimensions are part of the normal offer, not an exception.
Resistive-capacitive voltage sensors (RCVS) for medium voltage switchgear, cast in epoxy by Indisol
Where RCVS are used
Indoor applications, in the places where signal quality sets the limit.
Why the absence of a core matters
Ferroresonance is a resonance between the saturable magnetic core of an instrument transformer and the capacitance of the network around it. Once it starts, it produces sustained overvoltages that bear no relation to the system voltage, and it damages equipment.
The condition needs a core to saturate. An RCVS is a divider — resistors and capacitors cast in epoxy, with no iron and nothing to saturate — so the condition cannot arise. That is a different kind of answer from damping resistors and loading burdens: the failure mode is absent rather than managed.
The same absence is what gives the sensor its bandwidth. A wound transformer is designed around one frequency; a divider is not, which is why an RCVS holds its accuracy across a wide frequency range and can be trusted with waveform and harmonic information rather than only the fundamental.
Design options
Three things you can choose, and they are chosen per project.
Precision, safety and adaptability
RCVS combine precision, safety and adaptability: reliable voltage measurement and fault detection, without the ferroresonance risk that comes with a saturable core. In a new installation or a retrofit, that combination is what makes the choice future-proof rather than merely adequate.
Series parts are cast by gelation under pressure at temperature, which is what keeps the divider ratio and the dielectric behaviour consistent across a whole production run instead of only on the first pieces. More on how we cast them.
Testing runs in house and in external laboratories under ISO 9001 and ISO 14001: industrial frequency, partial discharges to 200 kV, high voltage and current metrology, and contact resistance.
The other two sensor technologies
All three cover medium voltage. What separates them is what the signal is for.
The rest of what we cast
A voltage sensor is one of seven families of cast epoxy parts. Go straight to the right one.
Common questions
Send us the network voltage, the accuracy class and the envelope. We design the RCVS to them.
Every part we cast is engineered to a specification rather than selected from a catalogue, so you get a design proposal back, not a page number. You do not need all of the detail to start.
Request a quotation → or see how we cast them
