Wireless Control and Communication to Motor Protection Relays by using an Embedded Microprocessor

Newelec (Pty) Ltd is a three-phase induction motor protection relay manufacturer. The function of the protection relay is to capture running data, to provide protection, to control a motor and to communicate this data to the SCADA system in a control room. The protection relays are equipped with communication facilities to be used in an instrumentation environment. The ideal cost and time effective solution is to remotely perform these tasks via a reliable wireless network. The purpose of the research was to create a low cost wireless remote link between the remote site and a technician with the capability to communicate with any one of a range of electric motors. It became evident that a node controller with an effective protocol between the protection relay and the node controller and a global system for mobile communications (GSM) link would be able to solve the problem. The node controller provides connectivity for a maximum of 32 protection systems. The function of the node controller is to capture data, to administrate a database of time and date stamped faults and to exchange motor related data via the GSM network to a technician. GSM network is a public network and security in the form of password protection is employed to prevent unauthorized intrusions into the system. The technician is enabled to retrieve and transmit motor related data with a standard cell phone that proved to be very cost effective. The message transfers are done with short message system (SMS´s). This system keeps the technician in touch with the remote site, anywhere in South Africa where GSM coverage is provided