Every utility considering partial discharge monitoring asks the same question: what does it cost, and is it worth it? The answer is rarely a single number, because a monitoring system is built from several cost layers and the value depends on what it prevents. This article breaks down the cost structure and builds the ROI case in terms an asset manager can take to a budget review.
The cost structure
A PD online monitoring system has five cost layers:
- Sensors – the per-point cost of the sensing element. This is the largest variable: a simple TEV sensor on a panel costs far less than a combined UHF/TEV/ultrasonic/temperature sensor for a GIS bay.
- Acquisition and communication – the multi-channel units and IoT gateways that collect the sensor data and move it to the platform. One multi-channel unit or gateway typically serves many sensors, so this cost is shared.
- Platform and software – the monitoring software, licence and server. Modern platforms are a modest fixed cost, not a per-point cost.
- Installation and commissioning – mounting, cabling, configuration and threshold setting. This is often underestimated and can exceed the hardware cost on difficult sites.
- Operation – training, threshold tuning, alarm handling and periodic verification.
The practical consequence: the cost is dominated by the number of points and the choice of sensor, not by the platform. Starting with the critical points and a simple sensor type keeps the first phase small and measurable.
What drives the cost down
Several practical choices reduce the total cost:
- Staged rollout – monitor the critical bays first, expand later; the platform and gateway are shared.
- Shared infrastructure – one multi-channel unit or gateway serves a whole switchroom, so the per-point acquisition cost falls as the fleet grows.
- Combined sensors – a two-in-one or four-in-one sensor costs less than two or four separate sensors and one mounting point.
- Reuse of the platform – the same monitoring platform serves PD, temperature, gas and arrester data, so a later phase adds sensors without new software.
Building the ROI case
The value of PD monitoring is the cost of the failures it prevents, and the realistic comparison is:
- Cost of the system over its service life (hardware, installation, operation)
- Cost of one unplanned failure – the repair, the lost energy, the penalty for the outage, and the secondary damage to adjacent equipment
- Failure probability without monitoring – the historical rate for the asset class
For a critical transformer or a long cable circuit, the cost of a single unplanned failure typically exceeds the total cost of the monitoring system for the same asset by a large margin. The monitoring system does not have to prevent many failures to pay for itself; preventing one in ten or twenty years is enough.
Beyond the spreadsheet
There are also benefits that are hard to price but real:
- Maintenance can be planned instead of reactive – the outage is scheduled, not forced
- The crew arrives with the right tools because the diagnosis points to the location
- The condition data supports asset life decisions – replace, refurbish or continue monitoring
- Insurance and regulatory reporting benefit from documented condition evidence
Summary
The cost of a PD monitoring system is driven by the monitored points and the sensor choice, with the platform a shared fixed cost. A staged rollout, shared gateways and combined sensors keep the budget proportionate, and the ROI case rests on the cost of the unplanned failures the system prevents. HUWOR supplies sensors, gateways, platforms and handheld detectors as one family, so each phase builds on the last. Contact the HUWOR sales team for a costed proposal for your site.