Bourns® IsoMOV hybrid protection component is a fully integrated GDT and MOV hybrid design. It is a remarkable innovation in MOV device design and offers an advanced protection solution that decodes MOV degradation issues while significantly increasing surge performance, device reliability, and operational life. For the IsoMOV product design, Electronic Products awarded Bourns The 2021 Product of the Year Award in the Passives Category.
Figure 1: Circuit Diagram & Schematic Symbol of IsoMOV Hybrid Protector (Image Source: Bourns)
IsoMOV hybrid protection components combine the best features of the breakthrough surge performance EdgMOV technology with an integrated Gas Discharge Tube (GDT) isolation structure and offer high reliability and long life, including in certain demanding environments. In this configuration, the GDT blocks leakage currents through the MOV that would otherwise lead to premature failure of the MOV device, while the MOV prevents the follow-on current (after a surge) that might damage the GDT. The design creates the equivalent function of a discrete MOV and GDT in Series Using proprietary computer-aided design techniques to model performance. After assembly of the core, leads are attached, and the unit is epoxy coated. The result is a familiar radial disc MOV package with a slightly thicker and substantially smaller diameter than similarly rated conventional devices.
By integrating a MOV with a GDT, the hybrid device is tolerant of AC line voltage swells. Also, it offers low capacitance for low insertion loss, which is a clear advantage in power line communication applications. Plus, the low capacitance of the GDT assures that the IsoMOV surge protector will not impede AC or DC power line high-speed data rates. Figure 2 shows the construction of the IsoMOV hybrid protector.
This Series upgrades nearly any MOV power application where premium performance and/or space savings are important. The extended temperature range, low leakage, and superb energy handling density are especially advantageous to industrial and other applications exposed to high surges.
Figure 2: The construction of the IsoMOV protector (Image Source: Bourns)
The IsoMOV device's unique and graceful end-of-life failure mode quickly and cleanly blows the line fuse, never leaving equipment unprotected and eliminating the need for any indicator circuitry.
This protector family includes three unique Series of devices; Model IsoM3, IsoM5, and IsoM8. With nominal surge ratings of 3 kA, 5 kA, and 8 kA, these revolutionary new protectors offer performance usually found in larger traditional MOV devices.
The surge ratings of IsoMOV protectors are comparable to the surge ratings of the next larger size of conventional MOV devices. This offers designers the flexibility of choosing an IsoMOV protector that is smaller than the MOV option or choosing an IsoMOV protector of the same size as the MOV option and enhancing the surge capability of their protection scheme.
Many systems use 3-phase power due to its cost-efficiency and load balancing advantages. Like all electrical equipment, 3-phase AC systems require protection from voltage transients. For these designs, Bourns® IsoMOV hybrid overvoltage protectors offer an excellent protection solution due to their clamping voltage performance along with low leakage and low capacitance in a small form factor.
Figure 3: A 3-phase Y-Configuration (Image Source: Bourns)