Multifunction dynamoelectric protection system

A protection system for a deynamoelectric machine comprising

• a source of power and switching means for switching the power to and from the dynamoelectric machine,
• control means adapted to control the switching mmeans comprising first and second voltage comparators each having two inputs and an output, a source of d.c. power, a first voltage divider connected between the d.c. power source and common comprising a reference resistor and a temperature dependent resistor forming a first junction therebetween, the first junction connected to one input of the first comparator, a second voltage divider ccomprising two resistors forming a second junction therebetween, the second voltage divider serially connected to another resistance, the voltage divider and the said another resistor connected between the d.c. power source and common, the second junction connected to one input of the second comparator, reference voltage means connected to the other inputs of the first and second comparators, a diode coupled between the first and second junctions, the output of first comparator connected to a point between the second voltage divider and the said another resistance, so that upon a selected change in temperature and concomitant change in resistance of the temperature dependent resistor or upon shorting of the temperature dependent resistor, the output of the second comparator will switch and cause the switching means to interrupt power to the machine.

A protection system for a dynamoelectric machine comprising

• switching means for switching a source of power to and from the machine,
• a bridge circuit means controlling operation of the switching means, the bridge circuit means including a resistor bridge, the resistor bridge including a temperature dependent resistor responsive to a predetermined temperature condition,
• trigger means responsive to an unbalance of the bridge to operate the switching means,
• a time delay means having a time delay voltage comparator with two inputs and one output, a time delay voltage divider comprising two resistors forming a time delay junction therebetween, a diode, the inputs of the time delay voltage comparator connected to the time delay junction with the diode interposed therebetween, a capacitor connected across one of the two resistors of the time delay voltage dividers and the output of the time delay comparator coupled to the trigger means.

A protection system for a dynamoelectric machine comprising

• switching means for switching a source of power to and from the machine,
• a bridge circuit means controlling operation of the switching means, the bridge circuit means including a resistor bridge, the resistor bridge including a temperature dependent resistor responsive to a predetermined temperature condition,
• trigger means responsive to an unbalance of the bridge to operate the switching means,
• manual reset means having a manual reset voltage comparator with two inputs and an output, a diode connected between the two inputs of the manual reset voltage comparator, one input of the manual reset comparator connected through a resistor to a power source and to another resistor to the trigger means, the second input of the manual reset comparator connected to common through a capacitor and to the output of the manual reset comparator through a resistance, the ouput of the manual reset comparator coupled to the trigger means.

A protection system for a dynamoelectric machine comprising

• switching means for switching a source of power to and from the machine,
• a bridge circuit means controlling operation of the switching means, the bridge circuit means including a resistor bridge, the resistor bridge including a junction formed between a temperature dependent resistor responsive to a predetermined temperature condition and a reference resistor,
• trigger means responsive to an unbalance of the bridge to operate the switching means,
• output sensing control means comprising first and second output sensing voltage comparators each having two inputs and an output, a coil connected between two resistors which are in turn connected between a power source aand common, the two inputs of the first output sensing comparator connected to opposite ends of the coil, a power line carrying power to the machine disposed about the coil to form at least a single turn thereabout, the output of the first output sensing comparator connected through a capacitor to an input of the second output sensing comparator, the output of the second output sensing comparator coupled to the trigger means.

A protection system for a dynamoelectric machine which has a power supply, a solid state power switch adapted to energize the machine, the power switch having a control element, contacts adapted to move into and out of engagement connected to the control element, electromagnetic coil means coupled to the contacts to control their position, and a control current switch to control the engergization of the electromagnetic coil means comprising

• a temperature control network including a voltage comparator having two inputs and an output, at least one temperature dependent resistor adapted to provide a signal to one of the inputs of the temperature control comparator indicative of the temperature of the temperature dependent resistor,
• a shorted sensor control network including a shorted sensor voltage comparator having two inputs and an output, the output of the shorted sensor control comparator determining the state of energization of the control current switch,
• the output of the temperature control comparator coupled to one of the inputs of the shorted sensor comparator and adapted to control its output state so that subjection of the sensor to a preselected temperature will cause the temperature control comparator to switch from one state to another which will in turn cause the shorted sensor comparator to switch from one state to another deenergizing the control current switch and deenergizing the electromagnetic coil means so that the contacts move out of engagement to deenergize the power switch and the machine.