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Ohmic Voltage Sensor

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More than 15 years of experience in medium voltage sensors

The ohmic voltage sensor is a resistive divider cast in epoxy, engineered to mount as an end piece in the plug set. It gives the most accurate and most stable image of the medium voltage in our range: measured value deviation of 0.2% or 0.5%, with a standardised 3.25 V secondary output.

A resistive divider has no core to saturate and no capacitance whose ratio moves with frequency, so what appears on the secondary is a scaled copy of what is on the conductor. That is why this is the sensor to specify when the signal feeds a protection relay, a power quality analyser or a diagnostic system rather than a simple live-or-dead indication.

The modular design mounts as an end piece in the plug set, which makes it as straightforward in a retrofit as in a new panel — the sensor takes the place of a component that is already there instead of asking for space that is not.

Thermal stability is designed in. The divider holds its accuracy across a wide temperature range, so the deviation you specify is the deviation you get in service and not only on the test bench.

Send us the operating voltage, the deviation class and the secondary interface, and we will come back with the part that fits.

Ohmic voltage sensor as an end piece in a medium voltage plug set, Indisol

Medium voltage sensor components and a cast epoxy post insulator, Indisol

Range of cast epoxy medium voltage sensor insulators, Indisol

Voltage indicator panel and cast epoxy sensor insulator, Indisol

Ohmic voltage sensor as an end piece in a medium voltage plug set, cast in epoxy by Indisol

12–72 kV12, 24, 36 or 72 kV

0.2% / 0.5%Measured value deviation

3.25 VSecondary output

BNC / RJ45Secondary interface

Electrical characteristics

Three numbers settle most specifications.

Operating voltage12, 24, 36 or 72 kVFour standard levels covering medium voltage distribution. Tell us the system voltage and the insulation coordination you work to and we will confirm the creepage and clearance the part needs.

Accuracy0.2% or 0.5% deviationTwo classes, chosen by what the signal feeds: 0.2% for protection, monitoring that has to be trusted, and diagnostics; 0.5% where the requirement is looser.

Secondary side3.25 V on BNC or RJ45A standardised output level for monitoring equipment, on a pluggable BNC connector or an RJ45 interface — secure, low-noise signal transmission and simple integration with digital systems.

Where they are used

Medium voltage switchgear, where precise voltage measurement supports protection relays, control and automation. This is the tightest space in the panel and the reason a divider is used instead of a wound transformer.

Transformers, enabling continuous monitoring, diagnostics and fault detection — applications where a drifting signal is worse than no signal at all.

Secondary systems, particularly grid automation and digital substations, where stable and accurate signals are the input the whole system depends on.

Compatibility

The sensor is designed to fit what is already in the panel.

Plug setsMounts as an end pieceMechanical and electrical compatibility with widely used connector sets and components, including balanced plugs, Nexans, NKT, Südkabel and TE Connectivity.

New build and retrofitModular by designThe same part serves a new installation and a retrofit, which is what makes it practical to upgrade a panel that is already in service rather than replacing it.

Digital systemsStandardised output3.25 V with BNC or RJ45 keeps integration with existing monitoring and control systems a wiring job rather than an engineering project.

Performance and reliability

Advanced resistive divider technology gives long-term measurement stability, excellent linearity, and minimal influence from temperature variation — the three things that decide whether a measurement is still worth trusting after ten years in a panel.

The construction is robust enough for an extended service life with low maintenance, and the standardised output simplifies integration into monitoring and control systems that are already installed.

Testing runs in house and in external laboratories under ISO 9001 and ISO 14001, with industrial frequency and partial discharge capability to 200 kV. More on how we cast them.

The other two sensor technologies

All three cover medium voltage. What separates them is what the signal is for.

Ohmic voltage sensor mounted as an end piece in a medium voltage plug set, Indisol

Ohmic voltage sensorResistive divider. Lowest deviation — 0.2% or 0.5% — with a 3.25 V standardised output. For protection, monitoring and diagnostics.You are here

TSK capacitive insulator and KKE capacitive coupling electrode in cast epoxy, Indisol

Capacitive voltage sensor (TSK / KKE)Capacitive divider. Compact voltage detection for VDS LRM and HR systems, with TSK units dimensioned as DIN insulator replacements.See the range →

Resistive capacitive voltage sensor RCVS in cast epoxy, Indisol

Resistive-capacitive sensor (RCVS)Both principles in one part. Classes from 1% to 0.2% over a wide frequency range, 17 to 72 kV, and no core to ferroresonate.See the range →

The rest of what we cast

A voltage sensor is one of seven families of cast epoxy parts. Go straight to the right one.

Support & post insulatorsHold a conductor away from earth and carry the mechanical load.See the range →

Medium voltage cast epoxy bushing, Indisol

BushingsTake a live conductor through a wall, an enclosure or a tank.See the range →

Cast epoxy components for gas insulated switchgear, Indisol

GIS productsBusbar supports, fuse tubes and breaker chambers inside gas insulated equipment.See the range →

Divider insulatorsInsulate and, at the same time, give a low voltage signal that follows the conductor.See the range →

Medium voltage voltage sensors and indicators in cast epoxy, Indisol

Medium voltage sensorsMeasure voltage or current to a stated accuracy class.You are here

Third rail insulator supporting a T-section conductor rail, Indisol cast epoxy

Third rail insulatorsHold the conductor rail that powers a metro or light-rail line.See the range →

Customized cast epoxy product for medium and high voltage, Indisol

Custom HV/MV productsEpoxy housings for switches, and shapes none of the above describes.See the range →

Common questions

Where does the sensor mount?As an end piece in the plug set. The modular design means the same part works in new installations and in retrofits.

Which deviation class should I ask for?0.2% where the signal feeds protection, monitoring that has to be trusted, or diagnostics. 0.5% where the requirement is looser and cost matters more.

What comes out of the secondary side?3.25 V, a standardised level for monitoring equipment, on a pluggable BNC connector or an RJ45 interface.

Will it work with our cable accessories?It is designed for mechanical and electrical compatibility with widely used connector sets, including balanced plugs, Nexans, NKT, Südkabel and TE Connectivity. Tell us what you use.

Does the accuracy drift with temperature?The sensors are designed to maintain high accuracy across a wide temperature range, with minimal drift under varying operating conditions.

Ohmic or capacitive?Ohmic when you need an accurate, linear measurement. Capacitive when you need compact, cost-efficient voltage detection. Resistive-capacitive when you want both from one part.

Send us the voltage, the deviation class and the interface. We will design the sensor 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

Useful to includeThe operating voltage — 12, 24, 36 or 72 kVThe deviation class — 0.2% or 0.5%The secondary interface — BNC or RJ45Which plug set or connector system you useQuantity, and whether this is a new panel or a retrofit