Detector-protector circuit

Claim 2

In a system for controlling electrical power flow to a plurality of independent electrical systems forming a group and each having a limit switch connected across a power source that opens upon malfunction of its associated system, an alarm for interrupting power flow to all of the systems in said group when one of the systems malfunctions and for producing a visual indication to identify the particular malfunctioning system, said alarm comprising: a malfunction indicator lamp associated with each system in said group; a first relay associated with each system in said group and having a first set of normally closed contacts and a second set of normally open contacts, said first contact sets of all first relays being connected in series with one another and with the electrical power flow circuit to said group of systems and said second contact set of each first relay being connected to a power source and the associated indicator lamp to energize the lamp upon closure of the contacts; and monitoring means connected across the limit switch of each system in said group and to the associated first relay of each system for energizing said first relay upon opening of the switch to interrupt the electrical power flow path to said group and illuminate the lamp associated with the malfunctioning system.

Claim 3

The alarm set forth in claim 1 wherein: each of said first relays include a third set of normally closed contacts and a fourth set of normally open contacts, the fourth contact set being series connected between a current source and the coil of its firSt relay; and each of said monitoring means includes a second relay having a normally open contact set connected across the fourth contact set of said first relay, the coil of said second relay being connected in series with the power source across the associated system limit switch and the third contact set of said first relay to energize said second relay upon opening of the limit switch and operate said first relay through the second relay contact set, said first relay being latched operated through its own fourth set of contacts.

Claim 4

The alarm set forth in claim 2 wherein each of said monitoring means includes a bridge rectifier having its input connected across the system limit switch and having its output connected to the coil of the second relay through the third contact set of the first relay.

Claim 5

In a system for controlling electrical power flow to a polyphase electric motor, an alarm for interrupting power flow to all phases when a malfunction occurs in power flow to any one of the phases and for producing a visual indication to identify the particular malfunctioning phase, said alarm comprising: means having a pair of control terminals for supplying power to all phases of said electric motor in response to connection across said terminals; a malfunction indicator lamp associated with each phase of said motor; a relay associated with each phase of said motor, each relay having first and second sets of normally open contacts, said first contact set of each relay being serially connected between its associated lamp and a power source and the second contact sets of all of said relays being connected in series with one another and with the control terminals of said motor power supply means; a start relay having a normally open contact set connected across said control terminals and a coil serially connected with a power source, a timing circuit and a start switch, said relay only remaining operated for a preselected period of time after closure of said start switch; and monitoring means associated with each of the phases and responsive to power flow through its phase for operating the associated relay to close its second contact set and thereby complete the series path between said control terminals only if all relays are operated, said power supply being interrupted if all relays are not operated prior to the end of said preselected period of time.

Claim 6

In a system for controlling electrical power flow to a polyphase electric motor, an alarm for interrupting power flow to all phases when a malfunction occurs in power flow to any one of the phases and for producing a visual indication to identify the particular malfunctioning phase, said alarm comprising: means having a pair of control terminals for supplying power to all phases of said electric motor in response to connection across said terminals; a malfunction indicator lamp associated with each phase of said motor; a relay associated with each phase of said motor, each relay having first and second sets of normally open contacts, said first contact set of each relay being serially connected between its associated lamp and a power source and the second contact sets of all of said relays being connected in series with one another and with the control terminals of said motor power supply means; a start relay having a normally open contact set connected across said control terminals and a coil serially connected with a power source, a timing circuit and a start switch, said relay only remaining operated for a preselected period of time after closure of said start switch; and monitoring means associated with each of the phases and responsive to power flow through its phase for operating the associated relay to close its second contact set and thereby complete the series path between said control terminals only if all relays are operated, said power supply being interrupted if all relays are not operated prior to the end of said preselected period of time.

Claim 7

The alarm set forth in claim 4 wherein each of said monitoring means includes a gated semiconductor device connected in series with the coil of said relay and a source of current, the gate lead of said semiconductor device being connected to a coil positioned to monitor current flow to the associated phase of said motor.

Claim 8

The alarm set forth in claim 3 wherein said relay current source is alternating and said gated semiconductor device is a triac.

Claim 9

In a system for controlling electrical power flow to a plurality of independent electrical systems forming a group and each having a limit switch connected across a power source that opens upon malfunction of its associated system, an alarm for interrupting power flow to all of the systems in said group when one of the systems malfunctions, said alarm comprising: a first relay associated with each system in said group and having a first set of normally closed contacts and a second set of normally open contacts, said first contact sets of all first relays being connected in series with one another and with the electrical power flow circuit to said group of systems, and monitoring means connected across the limit switch of each system in said group and to the associated first relay of each system for energizing said first relay upon opening of the switch to interrupt the electrical power flow path of said group.

Claim 10

In a system for controlling electrical power flow to a plurality of independent electrical systems forming a group and each having a limit switch connected across a power source that opens upon malfunction of its associated system, an alarm for interrupting power flow to all of the systems in said group when one of the systems malfunctions, said alarm comprising: a first relay associated with each system in said group and having a first set of normally closed contacts and a second set of normally open contacts, said first contact sets of all first relays being connected in series with one another and with the electrical power flow circuit to said group of systems, and monitoring means connected across the limit switch of each system in said group and to the associated first relay of each system for energizing said first relay upon opening of the switch to interrupt the electrical power flow path of said group.

Claim 11

In a system for controlling electrical power flow to a polyphase electric motor, an alarm for interrupting power flow to all phases when a malfunction occurs in power flow to any one of the phases, saiD alarm comprising: means having a pair of control terminals for supplying power to all phases of said electric motor in response to connection of a series path across said terminals; a start relay having a normally open contact set connected across said control terminals and a coil serially connected with a power source, a timing circuit and a start switch, said relay only remaining operated for a preselected period of time after closure of said start switch; and a gated semiconductor monitoring device associated with said phases and connected to an associated relay having a contact set, said semiconductor device responsive to power flow through said phases for operating the associated relay to close its contact set and thereby complete the series path between said control terminals only if all relays are operated, said power supply being interrupted if all relays are not operated prior to the end of said preselected period of time.

Claim 12

In a system for controlling electrical power flow to a polyphase electric motor, an alarm for interrupting power flow to all phases when a malfunction occurs in power flow to any one of the phases, saiD alarm comprising: means having a pair of control terminals for supplying power to all phases of said electric motor in response to connection of a series path across said terminals; a start relay having a normally open contact set connected across said control terminals and a coil serially connected with a power source, a timing circuit and a start switch, said relay only remaining operated for a preselected period of time after closure of said start switch; and a gated semiconductor monitoring device associated with said phases and connected to an associated relay having a contact set, said semiconductor device responsive to power flow through said phases for operating the associated relay to close its contact set and thereby complete the series path between said control terminals only if all relays are operated, said power supply being interrupted if all relays are not operated prior to the end of said preselected period of time.

Claim 13

The alarm set forth in claim 8 and further comprising plural gated semiconductor monitoring devices connected in series with the coil of said associated relay and a source of current, the gate lead of said semiconductor device being connected to a coil positioned to monitor current flow to the associated phase of said motor.

Claim 14

The alarm set forth in claim 9 wherein said relay current source is alternating and said gated semiconductor device is a triac.

Claim 17

The system of claim 11 and further comprising a predetermined resistance connected between said current transformers and said triac device.