Switchgear operators need two pieces of information from the same point on a busbar: is it live, and is its insulation healthy? These two questions are traditionally answered by separate devices – a live display indicator on the panel and a partial discharge monitoring system behind it. The high-voltage live display PD terminal answers both from one monitoring point. This article explains the HUWOR HMJ1010-WCK.
One terminal, two functions
The HMJ1010-WCK is designed to reliably monitor the partial discharge of the A, B and C phase busbars in switchgear and ring main units, while also providing the live display function that tells the operator the busbar is energised. The two functions share the same sensing point on the busbar, which reduces the number of devices in the panel and simplifies the cabling.
For the PD function, the terminal monitors the discharge on each of the three phases, so an operator can see immediately whether the activity is on one phase (typical of a localised defect such as a bad termination) or on all phases (typical of a system-wide condition such as moisture or pollution).
Communication and integration
The monitoring terminal communicates via RS485 and supports the Modbus protocol, which makes it a natural fit for existing substation automation and SCADA environments. The terminal reports the phase-by-phase PD status to the monitoring platform, where the values are trended and alarmed, and the live display is available locally on the panel.
According to the published specification, the applicable ceramic capacitor range of the HMJ1010-WCK is 20 pF – 400 pF (up to 35 kV), measured under the reference conditions stated in the datasheet. The terminal is matched to the busbar coupling element during project design.
Where the HMJ1010-WCK is used
Typical deployments:
- Ring main units and switchgear panels where the live display is already required, adding PD monitoring at marginal cost
- Distribution substations where the operator needs phase-resolved PD status without a separate monitoring cabinet
- Retrofit projects where the existing panel has a live display location that can carry the combined terminal
In each case the benefit is the same: the PD channel is added to a device that is already part of the panel, so the monitoring point does not increase the panel footprint.
From terminal to complete system
The HMJ1010-WCK feeds the same HUWOR monitoring platform as the other sensors in the family. A project can start with the combined terminals on the most critical panels, then expand to a full monitoring system with multi-channel units, gateways and central software as the programme matures. The Modbus interface keeps the terminal compatible with third-party platforms as well.
Summary
The high-voltage live display PD terminal combines two panel functions in one device: busbar live indication and three-phase partial discharge monitoring, with RS485 Modbus communication for integration. The HMJ1010-WCK fits ring main units and switchgear panels up to 35 kV with a matched ceramic capacitor coupling. HUWOR supplies the terminal with OEM/ODM support. Contact the HUWOR sales team for a panel integration proposal.