The InsuLogix® B is a cost-effective, software-oriented,continuous on-line monitoring system for monitoring power factor at operating voltage in high voltage capacitive bushings and/or HV current transformers. The device acquires, analyses, and trends data pertaining to AC Insulation Power Factor of Bushings and/or HV current transformers.
BUSHING FAILURE MODES
The most common type of bushing failure occurs in the internal capacitive layers. These failures occur slowly over time with one layer failing and burning through the insulation. The InsuLogix® B provides advanced warning of bushing failure through sensors that detect early changes in the voltage amplitude and phase angle.
InsuLogix® B MONITORING TECHNIQUE
The InsuLogix® B monitors Power Factor/Tan δ from the bushing C1 Test Tap using algorithms that simulate the Schering Bridge technique, a standard industry method of offline testing. This standard based method provides early warning of a problem bushing. Online tests are performed at rated voltage, under load, and in all weather conditions, as opposed to offline testing which is performed at 10 V when weather conditions permit. This online test detects internal insulation failures or external issues such as surface contamination due to pollution. The condition of the bushing is displayed on a 0-100% scale indicating changes in the Power Factor/Tan δ.
BUSHING TAP SENSOR
The Bushing Tap Sensor forms a capacitive voltage divider between the operating voltage and the capacitance of the bushing. This sensor protects the test tap with quad redundant protection by using the voltage divider capacitors and two spark gaps. The sensor measures the condition of the bushing’s insulation by using Phasor Values to compute Power Factor.
The system’s trending algorithms provide early warning of changes to bushing insulation quality. The Condition Value of each bushing is calculated by trending the Power Factor/Tan δ measurements in combination with comparative changes from the sampled set of bushings. The condition value is displayed in an intuitive Green, Yellow, or Red status indicating the level of risk for each monitored bushing. When compared to other methods of bushing monitoring, such as the current sum method, The InsuLogix® B’s algorithms provide the most accurate and earliest indication of the condition of the bushing’s insulation integrity under all weather and environmental conditions.”