초록 ▼

The invention relates to novel electrical devices which are useful for example as heaters and temperature sensors, and which comprise at least two electrodes, at least one PTC element, at least one relatively constant wattage element, and at least one current-directing element which directs the curr

The invention relates to novel electrical devices which are useful for example as heaters and temperature sensors, and which comprise at least two electrodes, at least one PTC element, at least one relatively constant wattage element, and at least one current-directing element which directs the current, when the device is first connected to a source of electrical power, so that the effective initial resistance of the device is greater than it would be in the absence of said element. Thus the invention provides a solution to the problem of current inrush in applications of PTC devices in which substantial current passes through the device at operating temperatures. The invention also includes the use of the novel devices in applications in which current inrush is not a problem.

대표청구항 ▼

An electrical device which comprises (a) at least two electrodes which are connectable to a source of electrical power; (b) at least one PTC element; (c) at least one relatively constant wattage (RCW) element in physical contact with a PTC element; and (d) at least one current-directing (CD) element

An electrical device which comprises (a) at least two electrodes which are connectable to a source of electrical power; (b) at least one PTC element; (c) at least one relatively constant wattage (RCW) element in physical contact with a PTC element; and (d) at least one current-directing (CD) element between the electrodes; wherein when the electrodes are connected to a source of electrical power while the whole device is below its operating temperature or substantially immediately after such connection, the current path passes through at least one PTC element and at least one RCW element in contact therewith, with the resistance of that current path being greater than the resistance of the current path that would be adopted if the CD element between the electrodes was replaced by an element of the same shape but composed of the same composition as that RCW element; subject to the proviso that, if each CD element is composed of a relatively insulating composition, all cross-sections through at least one of the electrodes show at least a part of the surface of the electrode in contct with a PTC element or an RCW element.