Megger SMART THUMP ST25-30

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Overview

The SMART THUMP ST25-30 is a compact fault location system designed for medium voltage power cables. It offers two or three power sources and can be operated from either a vehicle-mounted or portable version. The three power sources include AC line voltage, an internal battery, or an external battery. When connected to AC, the portable ST25-30 operates and, if equipped with an internal battery, its 74 Ah internal battery gets simultaneously charged.

The ST25-30 is ideally suited for use in both URD systems as well as for feeder cables and small and medium size network type systems. The 12/5/25kV surge and 30kV DC Hipot testing, in combination with the ARM Multishot feature, qualify the ST25-30 for all types of cable insulation materials, including XLPE, EPR, and PILC. The main advantages of the ST25-30 are its solid HV performance, simple operation, automated fault locating process, capable of operation in rainy conditions, weight, ergonomics, and being self-contained.

This device provides pre-location techniques, such as inductive ARM, current decoupling ICE, and SMART THUMP. It offers sectionalizing capability (trouble shooting in URD loop systems, North America), acoustic pinpointing with the integrated 1650J surge generator, as well as HV DC for insulation breakdown detection, indication of insulation resistance, and LV cable ground fault locating/sheath testing/sheath fault locating (sheath locating requires optional receiver ESG-NT).

There are seven configurations available for the ST25-30, including three portable versions mounted on an integrated hand truck with large air tires, and four vehicle mount versions with either an integrated or a remote control head. The portable versions can be selected with one (AC Only with internal Isolation Transformer), two (AC with internal Isolation Transformer plus external DC/Internal Inverter), or three power options (AC, External DC, Internal Battery/Inverter, no internal Isolation Transformer). The vehicle mounted versions ST25-30 can be powered by AC (internal isolation transformer) from the vehicle (via customer provided inverter) or a generator system, or by AC and external DC depending on the customer's specification.

When installed into a vehicle, the ST25-30 also offers either an integrated or remotely operated control head with a separation of up to 12ft between the control head and the HV unit. The remote control head is installed in a Pelicase style instrument enclosure. This manual covers all models of the SMART THUMP ST25-30.

The SMART THUMP ST25-30 system combines the following features and functions as a fully integrated device:

Quick Steps, Expert Mode, and Manual Mode, allowing to address three levels of user skill. The Manual Mode is available in all units that are equipped with the optional Multishot feature; if set to this mode all TDR features are always available on the user interface and must be selected/adjusted by the user; the automatic adjustments known from Quick-Steps and Expert mode are disabled in Manual Mode. This mode caters to the group of users who prefer to set the TDR up according to their own experience and expertise.
Quick Steps and Expert Mode provide Automatic fault Pre-location and localization with regard to the two closest transformers (Sectionalizing software for MV circuits, optional).
Quick Steps and Expert Mode provide Automatic cable end and fault detection and localization.
DC test up to 30kV with automatic breakdown detection and insulation resistance measurement.
Pinpointing of high resistance faults in surge mode (0-12.5 or 0-25kV).
Ground Fault (Sheath) test with automatic breakdown detection (5kV max.).
Ground Fault (Sheath Fault) pinpointing (requires optional receiver ESG-NT) (5kV max.).
Integrated safety circuit for user's safety (F-OHM for verification of correct connections of Safety Ground and HV Return).
Optional external remotely operated safety device to shut off HV and ground system (remote Emergency Off function).
Operation from internal battery/inverter or from an external AC or external DC source (e.g. external battery).
Sturdy and dust/weatherproof enclosure for outdoor use, IP53.

The scope of delivery of the ST25-30 system comprises the following components:

HV output cable hard wired
Safety Grounding cable
AC Power cord
Owner's manual

Available Accessories: The following accessories can be ordered from Megger, if required:

Elbow adapter with 14 mm female MC connector, fits T1 terminations (NAFTA market): Used to connect HV output cable (Item number: 865000100100000 (15 kV), 865000200100000 (25 kV), 865000300100000 (35 kV)).
External safety device: Safety device with signal lamps, key switch, and EMERGENCY OFF switch (Item number: 893024147 and 890024896).

Technical Data:

DC Test voltage: 0 to 30 kV
Surge voltage: 0 to 12.5/ to 25 kV
Source current: 40 mA (up to 12.5kV), 20 mA (up to 25kV), 5 mA (between 25 and 30kV)
Insulation measurement: 2 kΩ to 10 MΩ
Surge energy: 1600J @ the maximum voltage in each of both surge levels (12.5kV/25 kV)
AC Power input: 100-264V, 50-60 Hz, 6.3A 230V fuses on line and neutral. IEC320-C14 inlet.
Battery after 74 Ah: Internal, hermetically sealed lead-acid gel type battery (12 V/74 Ah)
External DC Connectors: 10.0-14.4V, > 50A, M8 Terminals w/ Wingnuts
Operating time battery: 45 min (pinpointing) at full energy
Power consumption: 700 W
Display: 7", 1280 x 800 pixel High Brite TFT direct sunlight readable
Memory: >1000 traces
Interfaces: USB port
ST25-30 units range with Multishot feature: up to 180,000ft/52km
ST25-30 units with Single Shot Mode: 25,000ft/8.5km and 100,000ft/32km
Measuring resolution: 0.8 m (2.5 ft) at 80 m/µs (250 ft/µs)
Max. sampling rate TDR: 100 MHz
Update rate: 5 samples/second
Dynamic range: 64 dB
Output impedance: 64 Ω
Operating temperature: -20 °C to +50 °C/-4°F to +122°F
Storage temperature: -25 °C to +70 °C/-13°F to +122°F
Intended Environment: Indoor and Outdoor
Relative Humidity: 0-95% (non-condensing)
Operating Altitude: 0 to 2000 meters/6500 ft
Pollution Degree: II
Dimensions (W x H x D): 690 x 1165 x 600 mm
Weight: 187lbs/85kg to 264lbs/120kg depending on selected model, incl. all items required to operate the specific model, e.g. HV cable and safety ground cable.
Protection class (in accordance with IEC 61140): I
Protection rating (in accordance with IEC 60529): IP53 (open lid)

Maintenance: For installation and operation of the equipment, it is not necessary to open the enclosure of the instrument. Opening the enclosure will void the warranty and liability of the manufacturer. Connections and connectors must be tested according to all applying standards (international, national, and company own). Keep connectors and connections clean. Line and neutral on the AC power input are fused. The fuse form factor is 5x20mm and are each rated for 6.3A 250VAC slow.

Storage: If not in use, the system should be stored in a dust-free and dry environment. Humidity (condensation) by itself or in combination with dust can reduce critical distances within the equipment, which are necessary to maintain safe high voltage performance. Always store the unit at a full state-of-charge. Apply topping charge every six months.