Danfoss Drives - Page 1

MAKING MODERN LIVING POSSIBLE VLT® Broken Belt Feature VLT® HVAC Drive provides advanced broken belt detection for fans and compressors. If a broken belt condition is determined, the drive can send a warning to the operator or stop the motor if desired. The feature can work in either open or closed loop operation. Advanced broken belt detection is based on motor torque. Torque is a better indication of a no-load condition because it avoids the need to compensate for motors with poor power factor (high current) at low load. This feature can be used for any loss of load condition, such as a broken belt (fan) or broken coupling (pump). During a loss of load, the motor runs at a high speed in an attempt to produce flow and the motor torque is low because there is no load on the motor. Loss of load is detected when the drive’s output frequency is greater than or equal to 15 Hz and the motor torque is below the programmed broken belt torque value for a programmed period of time. No need for sensors, wiring and digital input Broken belt detection is usually done using either an air flow or differential pressure sensor in the duct or a current sensor on the motor leads. The Broken Belt detection function of the drive eliminates the need for an external sensor, wiring to the controller and a digital input. A hard-wired digital output from the drive or serial communications can be used to alert the operator or maintenance personnel about the problem. Easy programming The drive software makes programming the Broken Belt feature quick and easy by choosing Fan Features and then Broken Belt Function under the Quick Menu. Perfect solution for: – Intelligent control – HVAC system protection – Remote status reporting Feature Eliminates need for an external sensor Reduced wiring Alerts operator of a warning or alarm Pre-programmed software for easy setup Benefit – Reduced installation and maintenance cost – Reduced installation cost – Improves operation of equipment – Improves occupant comfort – Saves time and increases reliability Facts about our products

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