SCM — partial discharge monitor for MV switchgear, cables and busducts, up to 60 channels
SCM (Switchgear & Cable Monitor) is a continuous partial discharge monitoring system for the insulation of medium-voltage equipment, namely switchgear, cables, busducts and packaged substations. The monitor records, stores and correlates PD data with operating conditions. It is used at industrial plants, data centres and power stations.
- PD channels
- 15 per module, up to 60 (4 modules)
- Dynamic range
- 70 dB, from 3 mV to 10 V without gain adjustment
- Phase resolution
- 7.5°
- Measurement band
- 1–20 MHz
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The insulation of switchgear, unlike the insulation of motors and generators, does not withstand destruction by partial discharges. A switchgear failure usually means a long outage, especially on old equipment for which spare parts often have to be custom-made. On cable lines, 90% of failures occur at joints and terminations, which as a rule generate discharges before they fail. Continuous PD monitoring gives time to plan repairs before an accident.
The SCM is supplied with one, two, three or four modules of 15 independent channels each with simultaneous sampling, up to 60 PD inputs in total. Dynamic range is 70 dB (from 3 mV to 10 V) without gain adjustment, measurement band 1–20 MHz, phase resolution 7.5°, 32 amplitude windows and internal memory 8 MB. Power supply 90–264 V AC 47–63 Hz or 120–300 V DC, operating temperature from −40 to 70 °C without additional heaters or coolers. Communication via Ethernet, USB and RS-485 with Modbus or DNP 3.0 protocol, and dry relay contacts signal the health of the monitor and alarm states.
Switchgear usually uses coupling capacitors distributed through the structure, typically one set per three sections. Cables are monitored with RFCT high-frequency current transformers on the termination screens, and if the screens are not earthed, GPCS sensors are installed. How far along the cable discharges can be seen depends on cable condition, insulation type and screen design. The monitor suppresses interference, including crosstalk between channels, and with central placement one SCM covers several switchgear sections. The basic supply includes an auxiliary current transformer and humidity and ambient temperature sensors.
Results are presented as two-dimensional, three-dimensional and polar phase patterns, histograms of pulse amplitudes and trends of amplitudes, pulse counts and discharge intensity. A Windows program is used for setup, data download and analysis. The monitor is supplied standalone, on a mounting panel with circuits brought out to terminals, or in a NEMA 4X cabinet. Each SCM can be assembled, configured, mounted and tested in the chosen version before shipment, which reduces work on site. Together with the SWGM switchgear monitor, the system adds oscillogram recording and breaker performance analytics.
Technical specifications
| PD channels | 15 per module, up to 60 (4 modules) |
|---|---|
| Dynamic range | 70 dB, from 3 mV to 10 V without gain adjustment |
| Phase resolution | 7.5° |
| Measurement band | 1–20 MHz |
| Amplitude windows | 32 |
| Power supply | 90–264 V AC (47–63 Hz), 120–300 V DC |
| Internal memory | 8 MB |
| Operating temperature | from −40 to 70 °C |
| Communication | Ethernet, USB, RS-485; Modbus or DNP 3.0 |
| Versions | standalone, panel-mounted, NEMA 4X cabinet |
Request a price and lead time
SCM — partial discharge monitor for MV switchgear, cables and busducts, up to 60 channels. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
How many PD channels can the SCM have?
From 15 to 60, that is, from one to four modules of 15 channels each with simultaneous sampling. With central placement, one monitor covers several switchgear sections.
Which sensors are used to monitor cables?
RFCT high-frequency current transformers on the termination screens, and GPCS sensors where the screens are not earthed. Coupling capacitors are usually used for switchgear.
What are the measurement chain parameters of the SCM?
Dynamic range 70 dB (from 3 mV to 10 V) without gain adjustment, band 1–20 MHz, phase resolution 7.5° and 32 amplitude windows.
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