Jul 19, 2011 ... CT1 measures 100µA and CT2 (which is just past the defect/fault) mea- ... The
IDL System is controlled by a laptop PC with LabView software ...
Insulation Defect Locator, IDL-2x50-100 Dual Clamp-On Direct-Current MicroAmmeter Transducers for Insulation Leakage Current Localization Operating Principle
This system has been designed for use with, but is not limited to, large hydo generator stator windings.
CT1
I I
HV
10 kV
100M CT2
0.5uF
Figure 1: Schematic for the Coil Array Test, Leakage Resistance “above” CT2
Figure 2: Example Print-Screen for Figure 1 Schematic For example, with a 100Mohm resistive leakage path to ground, the leakage current, I, is 100µA when the applied potential is 10kV. CT1 measures 100µA and CT2 (which is just past the defect/fault) measures zero. The capacitance from the windings to ground, shown as 0.5uF in this example, is initially charged by a current which is measured by CT1 and CT2. In the screen display corresponding to this example, the upper trace for CT1 shows the 100µA dc resistive current following the approximately 300µA peak capacitance charging current. The lower trace for CT2 shows the capacitive current, but no dc resistive leakage current. European Distributor: SenisGmbH; Technoparksrtrasse 1,8005 Zurich, Switzerland; www.senis.ch; tel +41 44 5087029 Americas Distributor: GMW Associates: 955 Industrial Road,1 San Carlos, CA 94070, USA. www.gmw.com. +1 (650) 802-8292 Revision Date: July 19, 2011
Insulation Defect Locator, IDL-2x50-100
The Ametes Insulation Defect Locator (DFL) utilizes two high sensitivity clamp-on microammeters to indirectly measure and track direct current passing through a defect or fault in the insulation system and determine the position of a leakage current path to ground. The DFL is capable of being used with the insulation system energized to high voltage. By indirectly measuring the leakage current, the defect or fault can be located without cutting conductors or removing insulation. This avoids the “divide-and-test” methodology, allowing the user to locate the defect quickly and significantly reduces repair time and effort.
Insulation Defect Locator, IDL-2x50-100 System Description The IDL System is controlled by a laptop PC with LabView software to control the High Voltage Power Supply output voltage and to acquire the instantaneous current outputs from the two MicroAmmeter Current Transducers. The software includes averaging of the current readings and presentation of the data with selection of the scaling for the current versus time display. To ensure that the capacitive charging current is maintained within the linear range of the current transducers, the software generates a smooth, selectable ramp profile for the High Voltage Bias Power Supply output voltage. A fiber-optic USB link from the laptop USB port to the System Interface Cabinet provides electrical isolation and any desired cable length.
100H
ISO Amp+ Input module 100E 100E Ramp control
ISO AM
HV supply
Power module 220/110V
Control Computer
Power supply +12V, -12V,+5V
System Interface
Current Transducers
Figure 3: Block Diagram of IDL System European Distributor: SenisGmbH; Technoparksrtrasse 1,8005 Zurich, Switzerland; www.senis.ch; tel +41 44 5087029 Americas Distributor: GMW Associates: 955 Industrial Road,2 San Carlos, CA 94070, USA. www.gmw.com. +1 (650) 802-8292 Revision Date: July 19, 2011
Insulation Defect Locator, IDL-2x50-100
Analog In 2
USB
Analog Out 1
USB via fiberoptics (Baaske)
Analog In 1
USB
Analog Out 2
DAQ module
Insulation Defect Locator, IDL-2x50-100 Cables up to 15m length from the System Interface (SI) to the Current Transducer 100E Amplifiers enable the interface to be located conveniently, even when the Current Transducers are moved to different locations in a large electrical system. Normally the System Interface can be left in the Transit Case and near the High Voltage Bias Power Supply. All connections to the System Interface, including the 115V/230V ac power, are accessible from the front panel.
Figure 4: System Interface (SI) with Modules
Figure 5: Application on Electrical Generator Stator. The two 100H Current Transducer Heads are shown installed on the winding links. Reprinted by permission from the US Department of the Interior, Bureau of Reclamation (USBR). European Distributor: SenisGmbH; Technoparksrtrasse 1,8005 Zurich, Switzerland; www.senis.ch; tel +41 44 5087029 Americas Distributor: GMW Associates: 955 Industrial Road,3 San Carlos, CA 94070, USA. www.gmw.com. +1 (650) 802-8292 Revision Date: July 19, 2011
Insulation Defect Locator, IDL-2x50-100
Short cables from the 100E Amplifiers to the 100H Current Transducer Heads enable the dimensions and weight of the head to be minimized to provide maximum flexibility in locating and orienting the 100H Heads in a complex winding geometry such as the generator stator shown.
Insulation Defect Locator, IDL-2x50-100 IDL-2x50-100 System Features: •
Two clamp-on 50-100 Current Transducers to enable current difference measurements in electrical conductors at high voltage.
•
Conductors do not have to be cut or insulation removed.
•
Simultaneous current measurements enable defect or fault location in complex systems, even with more than one leakage path to ground.
•
Computer control via fiber-optic isolated USB interface for electrical isolation and operator safety.
•
High Voltage Bias Power Supply output ramp profile programmed from the computer to provide reproducible, smooth voltage ramps to avoid high current capacitive charging transients.
•
Data acquired and displayed in real time for immediate analysis.
Specifications: 50-100 MicroAmmeter Current Transducer
•
Clamp-on Head Separable into Two Parts
•
Aperture Diameter: 51mm
•
Dimensions: 152mm x 96mm x 62mm
•
Weight: 0.6kg
•
Output Cable to Amplifier: 1m
•
Sensitivity to External Magnetic Field:
