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New Overload Relay Functionality for Eaton’s PKE Increases Convenience of Motor-Protective Circuit-Breakers
- Published: Friday, 28 March 2014 12:17
The new PKE-XZMR, suitable for safety-critical applications, can be side mounted as an accessory on all PKE motor-protective circuit-breakers and motor starter combinations and is wired with the contactor of the motor to be protected.
In the event of an overload, the XZMR module receives the corresponding signal and disconnects the contactor, while the PKE motor-protective circuit-breaker remains switched on. This enables the user to clearly distinguish between the two causes of tripping - motor overload and short-circuit. Two manual and automatic acknowledgement options are provided for resetting the fault. Automatic acknowledgement of the fault removes the need for opening of the switch cabinet in order to switch on the motor-protective circuit-breaker and simplifies plant monitoring, especially in areas that are difficult to access.
Before overload tripping can occur, the PKE-XZMR LED indicates over currents in the load circuit. This makes it possible to implement predictive maintenance of the drive and thus reduces possible downtimes. The XZMR module is equipped with an N/C contact for the contactor and an N/O contact for the overload signal.
The PKE-XZMR can be used both with the enhanced motor protection blocks (PKE-XTUA up to 65A) as well as with the enhanced system protection blocks (PKE-XTUACP up to 65A).
The PKE-XZMR module provides the PKE motor-protective circuit-breaker with two important convenience functions. The first is the possibility of predictive maintenance with an impending overload. In the event of an overload, the XZMR distinguishes between load currents greater than 100 per cent and load currents greater than 105 per cent, and indicates both with different flash frequencies via the integrated “Status” LED. Thanks to this early warning system, users can introduce preventative maintenance measures early in order to avoid any unnecessary downtimes.
The second convenience feature is the automatic restart of the motor after the contactor has tripped in the event of an overload. The type of restart of the XZMR module can be set directly on the device: In “Auto” mode, the resetting of the contactor after an overload is fully automatic and can restart immediately as soon as the module initiates the corresponding release signal. This saves valuable time and enables the simple autonomous monitoring of plants. If the alternative “Manual” setting is selected the fault signal has to be acknowledged before a manual restart, making it particularly suitable for safety-critical applications.