InsulGard

The InsulGard predictive relay revolutionized predictive maintenance practices by introducing one continuous, online partial discharge (PD) monitoring system designed for the following medium voltage applications:

• Generators
• Motors
• Switchgear
• Unit substation dry-type transformers 
• Bus duct 
• Cable connections 

Continuous eliminates the chances of failures occurring between periodic test events. 

Online eliminates the inaccuracies of offline tests.

InsulGard also reduces the level of expertise required to analyze PD data with userfriendly software.

InsulGard technology works for you 24 hours a day, 7 days a week, 365 days a year.

The InsulGard system detects partial discharge activity online, with the entire electrical system energized—no offline testing necessary. It analyzes radio frequency (RF) signals emitted by the partial discharge pulses and measures pulse quantity and magnitude, then correlates the data to temperature, humidity and various other electrical system dynamics. If PD levels exceed programmable set points, alerts are initiated. With or without alerts, you can quickly view or analyze trends using InsulGard software.

The predictive relay works as a single, local device or in a communication network with multiple devices.

The most commonly used sensors include coupling capacitors and radio frequency current transformers (RFCTs). For rotating machinery, such as generators and motors, additional sensing technologies are available.

For sites with pre-existing sensors, the InsulGard predictive relay is fully compatible and can be instantaneously commissioned.

Available sensors for rotating machinery include coupling capacitors and RFCTs. The traditional sensor of choice is the coupling capacitor; with this sensor alone, InsulGard technology provides much broader coverage of the stator winding when compared with the competition.

An optional RTD module takes advantage of a third PD sensing technology that dramatically increases the coverage of the stator winding for maximum coverage.

Used alone or in combination, the PD sensors, along with sensors for humidity, load and temperature, connect to the InsulGard predictive relay for monitoring, data collection and analysis.

InsulGard is also compatible with variable frequency drives and can be used on motors running between 3 and 400 Hz.

Problems that partial discharge analysis can detect within rotating equipment include:

• Early stages of insulation deterioration
• Sparks in voids and between windings
• Corona on end windings

Typical Sensors used for PD detection in switchgear include coupling capacitors and RFCTs. Due to the nature of high frequency signals to attenuate, most switchgear lineups require multiple sets of Coupling capacitors, while RFCTs are placed in each outgoing feeder breaker section.

Used alone or in combination, the PD sensors, along with sensors for humidity and temperature, connect to the InsulGard predictive relay for monitoring, data collection and analysis.

Problems that partial discharge analysis can detect within Switchgear include:

• Discharges in air gaps (between bus and support window, for example)
• Discharges in Incoming bus ducts
• Surface tracking (on supporting isolator or bus insulation surface)
• Insulation problems in cable terminations
• Poor electrical connections (floating potentials)
• Insulations problems in potential transformers and current transformers