US3859565A

US3859565A - Fire pump control apparatus

Info

Publication number: US3859565A
Authority: US
Inventors: Lee A Henningsen
Original assignee: Firetrol Inc
Current assignee: Firetrol Inc
Priority date: 1973-08-20
Filing date: 1973-08-20
Publication date: 1975-01-07
Anticipated expiration: 1992-01-07

Abstract

A self-contained fire pump control apparatus connected across the power lines has in combination a manually operated first circuit breaker means that is coupled with the power lines. A second circuit breaker means is serially coupled with the first circuit breaker means and includes current responsive means to sense the current flowing in the power lines. The latter means opens the second circuit breaker if a predetermined current limit is exceeded. A third circuit breaker means is serially coupled between the second circuit breaker and at least one fire pump. The third circuit breaker means includes pump output responsive means to open and close the third circuit breaker.

Description

United States Patent 1191 Henningsen Jan. 7, 1975 FIRE PUMP CONTROL APPARATUS Primary ExaminerJames D. Trammell [75] Inventor A. Hennmgsen Attorney, Agent, or Firm-Allison C. Collard [73] Assignee: Firetrol,Inc.,Erie, Pa. 221 Filed: Aug. 20, 1973 [57] ABSTRACT A self-contained fire pump control apparatus con- [211 App]' 389,860 nected across the power lines has in combination a manually operated first circuit breaker means that is 52 us. Cl 317/13 R, 307/118, 317/38, coupled with the Power lines- A second circuit 340 41 breaker means is serially coupled with the first circuit 8 b k d l d [51] Int. Cl. H02h 9/00 Tea means an es Current responsive means [58] Field of Search 340/418, 419, 240; to Sense the current flowing fi Power l The 317 3 3 307 117 113 latter means opens the second circuit breaker if a predetermined current limit is exceeded. A third circuit [56] R fer n e Cited breaker means is serially coupled between the second 21:23:: 21:21:: 1 :31:; 2211122: 51151111111531? g sive means to open and close the third circuit breaker. 3,660I722 5/1072 Wilson et a1 317/38 X 14 Claims, 6 Drawing Figures l 3 21 AC l 74 I l8 1 l 2 l I ISOL ATING I I I I SWITCH I 38M 40 I 42 I I CIRCUIT BREAKER AND TRIPPING I I f SYSTEM (FlG.4l I

HANDLE I g w+ 22 380 400 I 420 I I 28 30 88 76 I e r- 1 POWER 1 3 MAIN CONTACTOR I RELAY T (POWER SOLENOID) I l "-1:: t J I s4 82 I m I a I l PRESSURE I CON'TROL PUMP MOTOR l AC POWER l h l PATENTEDJAN 11915 3.859.565

I SHEEI 1 BF 3 I (ADJUSTABLE) Ho 1 TRIP AREA T I A v INSTANT PICKUP l4-I9ac (FIXED) M 6-8ac E 5905 I/240socL i A 3k S x 9' l2: 9 00 90 CURRENT 'PATENTEDJAH H915 3.859.565

SHEET 2 UP 3 A J v a 72 FIREPUMP BREAKER c F" "56?? I I a a a l FLUX TRANSFER SHUNT TRIP I 0 50 Z41 ERIE; I MONITORS I POWER TRIP CIRCUIT SUPPLY- 5i I AND I 46 I 58\ y 8:1 LONG DELAY TIME I AUXILIARY J l l N TRANSFORMERS 52 I INSTANTANEOUS TRIP l I STATIC SENSOR 56I L. R I A a c LOAD 50 IIIII'I'IIIIIIIII i I I l I I I l I I I I I PMENTEUJAPI H875 3.859.565 SHEEI 30F 3 3 in AC I 74 I l I 2 ISOLATING I SWITCH 38-\ -4o CIRCUIT BREAKER 20 AND TRIPPING f SYSTEM (FIG.4)

HAND E M AC 0 M 0 zz 380 400 I POWER 88 V 76 as I- t I POWER 7 MAIN CONTACTOR RELAY i W (POWER souawom) I L I I l 84 82 m I I I I PRESSURE TIMER PUMP CONTROL PUMP t V MOTOR AC POWER- i] so 7a FIR E' IUMP CONTROLAPIARATUS This invention relates to control of fire pump apparatus and more particularly to an automatic emergency control for fire pumps in modern high-rise structures.

In has been found that the pumping apparatus for fire equipment often times remains unused for extended periods of time. Owing to bearing congealment and start-up loads, an emergency demand for water pressure may cause excessive currents to flow in the pump motors and associated wiring. These excessive currents may cause the wires to exceed their load rating and excessively heat or ignite.

' Accordingly, the present invention is designed to overcome these difficulties and allow predetermined excessive currents to flow to the'pumps for predetermined times. In the event the current draw exceeds these pre-set limits, the apparatus will be automatically disconnected from the power lines. This is accomplished by having a plurality of sensing means used for monitoring the amount of current drawn by the pump apparatus. The output of the sensing means is applied to a control current that allows for various predetermined current levels to exist in the pump power lines.

The present invention contemplates the use of a single enclosed apparatus containing the operative components that comprise the current monitors, the isolating switch, the circuit breaker and current breaker control circuit, the main contactor, the pressure transducer, the timer and the power relay.

Thus, in the inventive design current monitors mount on the bus of the circuit breaker and continually sense the current flowing through the three-phase incoming power lines. At overload, the output of the current monitors rises approximately proportionately to the overload existing in the circuit breaker bus. The output of the current monitors is fed to a solid state tripping system that is designed to allow no more than 12 times the normal current to flow through the circuit breaker bus for short time intervals before the apparatus causes the circuit breaker to automatically trip. Automatic tripping will disconnect the current applied to the main contactor or power solenoid. The inventive circuit breaker will cause the main power lines to be disconnected on any current level exceeding 3 times normal motor running current after a time delay. At the 3 times normal motor running current level, current will be allowed to flow for 40 60 seconds before the solid state tripping system causes the circuit breaker to open. At the 6 times motor running current level, current will be allowed to flow for 12 20 seconds before the solid state tripping system causes the circuit breaker to open. At the 9 times motor normal running current level, current will be allowed to flow for 3 9 seconds before the solid state tripping system causes the circuit breaker to open. At any current value exceeding 12 times motor normal running current (up to rated interrupting capacity), the solid state tripping system will cause the circuit breaker to open in less than one second.

Combined with the above, the present invention provides for a main contactor or power solenoid. The power solenoid is serially placed between the circuit breaker and pump motor or motors. The power solenoid is controlled by various means which include an emergency start and stop button, an emergency run handle, and a pressure control device that is responsive to and monitors the fire pump pressure output. The. pressure control device senses the output pressure of thevarious firepumps and provides for automaticconnection and disconnection from the main power linein the event of a drop in fluid pressure. The pressure control device includes a timer so that the instantaneous variations of pressure existing in the pump output will not cause immediate actuation or disconnection of the power solenoid and the pump motor will be able to reach full speed and run for a preset short time interval.

Further the apparatus provides for a manual operated isolating switch to electrically remove the line from the load. And, a manually operated circuit breaker handle provides for the opening or closing of the circuit breaker contacts on demand.

In the event that a severe emergency arises, the inventive apparatus contemplates the emergency run handle being manually actuated allowing the mechanical closing of the main contactor independent of any control circuits.

It is therefore an object according to the present invention to provide an automatic across the line fire pump control apparatus.

. It is a further object of the present invention to provide a completely self-contained apparatus allowing both automatic and manual operation for controlling the power applied to fire pumps.

It is a still further object of the present invention to provide a device that continually monitors the current flowing through the fire pumps and allows the current level drawn by the pumps to exceed predetermined limits for predetermined intervals.

Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood however, that the drawings are designed for the purposes of illustration only and not as a definition of the limits of the invention to which reference should be made to the appended claims.

In the drawings wherein similar reference characters denote similar elements through the several views:

FIG. 1 is a prospective view of the self-contained fire pump control according to the inventive design showing the positioning of various parts;

FIG. 2 is a perspective view of the circuit breaker but removed from the housing of FIG. 1 and showing a static sensor connected to a current monitor;

FIG. 3 is a plot of current versus time showing the relationship thereof;

FIG. 4 is a block diagram with some components in the schematic and generally indicating the electrical interrelation of the static sensor, shunt trip solenoid, current monitors and the fire pump circuit breaker;

FIG. 5 is a front elevational taken in section and showing the shunt trip solenoid in combination with the inventive apparatus; and,

FIG. 6 is a block diagram of the operation of the components'contained in the housing of FIG. 1.

Referring now to the drawings and in particular FIG. 1 there is shown a housing 10 that in the preferred embodiment is supported by means of feet 12. A door 14 is hinged on housing 10. Door 14 contains a plurality of apertures 16 through which connecting

handles

18 and 20 are disposed as shown.

An emergency run handle 22 communicates through the forward face of housing 10. Also included on the 'for'wardfface of housinglofis an optional alarm system that might comprisevisual indicator'24 or a bell 26 or both. Adjacent to-the alarm system is a stop" button 28, a start button 30 and a power on pilot light 32. The inventive design also contemplates an alarm silence device indicated at 24a.

Referring now to FIG. 2 there is shown a circuit breaker 34 of thepresent invention. Circuit breaker bus 34 contains a breaker trip handle 36 that is designedto open and close electrical

connectionbetween bus powerlines

38, 40 and 42 with

bus lines

38a, 40a, and 42a. Referring back to FIG. I, handle comprises a circuit breaker lever that is mechanically coupled to switch tongue 36. Thus, it will be apparent that rotating handle 20 will cause circuit breaker 34 to open or close or reset the circuit between

lines

38, 40 and 42, with

lines

38a, 40a, and 42a.

A current monitor 44 is positioned about and inductively coupled to power-

line

38 and 38a as shown. It is to be understood, however, that while only one current monitor is shown, in use, the

other power line

40a and 42a will each contain a current monitor.

Referringnow to FIG. 4 there is shown

current monitors

44, 46 and 48 positioned about their

respective power lines

38, 40 and 42. The signals, if any, inductively coupled in either or all

coils

44, 46 and 48 are applied to a trip system 50 and hence across an auxiliary transformer 50a that contains a plurality of windings. In transformer 50a, the current induced from the monitors is stepped down to the milliampere level. Auxiliary transformer 50a contains a bridge rectifier circuit 50b, as is common in the art, to convert the AC transformer output to direct current. The rectified output of auxili ary transformer 50a is applied to a power supply and signal generator 52. Supply and generator52 provides power for energizing trip coil 62, which will be described hereinafter, and supplied a signal for both a long delay pickup 54 and an instantaneous trip 56.

As shown in FIG. 4, long delay pickup 54 is coupled with a long delayed time 58, the output of the latteris coupled with instantaneous trip 56 and thence applied to and forms the input-to trip circuit 60. The output of trip circuit 60 is applied to asolenoid or trip device 62. Trip device62 is contained in and automatically operates breaker 34.

Solenoidor trip device 62 is shown enlarged in FIG. 5. Trip device 62 contains permanent magnets 68 and a magnetic armature 66 a portion of which, 66a, is disposed between magnets 68. A pulse coil 64 containing a plurality of windings has its input connected across trip circuit 60 as seen in FIG. 4. The orientation of the magnetic field of permanent magnets 68 in conjunction with magnetic armature extensions 66a is such that armature 66aurges armature body 66 upwardly when looking at FIG. 5. A compression spring 70 is carried along the periphery of a portion of armature 66 extending outside of trip frame 62. The confining of spring 70 about armature 66 issuch that the co-acting forces of magnet 68 with magnetic armature 66 is slightly greater than the compressive force exerted by spring 70 against armature 66. However, when a current appears in coil 64, the magnetic field excited in pulse coil 64is directed so as to weaken the magnetic field exerted on armature 66a. This will cause spring 70 to force armature 66 downwardly when looking at FIG. 5,

Armature 66 is coupled to a trip bar,schematically represented by numeral 72 in FIG. 4. Solenoid 62 and trip bar 72 is contained in circuit breaker bus 34 as above mentioned, and operates to open the circuit exlating switch 74 is serially connected between

power lines

38, 40, 42 and bus 34. Switch 74 is adapted to isolate the combination of

power lines

38, 40, and 42 from a remote power source. It will be seen that the circuit breaker bus 34 is fed from isolating switch 74.

Handle 20 mechanically coupled with circuit breaker switch 36 provides manual means for operating and resetting circuit breaker 34. In addition to manualmeans 20 for interrupting the current flowing through circuit breaker bus 34, tripping system 50 as seen in FIG. 4, in conjunction with trip plunger 62 provides automatic interrupting capability for circuit breaker 34. This automatic system is responsive to the amount of current drawn by the fire pumps.v

Electrically connected with the output leads of circuit breaker 34 is a main contactor or power solenoid 76. Electrically coupled with and powered from main contactor 76 is a pump motor 78, the output of the latter mechanically driving pump 80. The pressure existing at the output of pump 80 is sensed by a pressure control 82. Pressure control 82 provides a signal when the. pump output pressure dropsbelow a preset pressure level. This signal is applied to a minimum period timer 84 having its output connected to a power relay 86. The output of power relay 86 is coupled to power solenoid or main contactor 76 as shown. Power solenoid 76 contains a contactor armature 88 the operation of which is controlled by either power relay 86, the operation of which is described below, or emergency run handle 22. v

Emergency run handle 22 provides a manual means for electrically isolating power lines 38a,'40a and42 a from pump motor 78. Referring back-to FIG. 1 it will be seen that emergency run handle 22 extends from frame 10 and is designed for convenient access.

As seen in FIG. 6 both start button 30 and stop" button 28 are serially connected with a remote power source. Thus the start and stop" button operating in conjunction with the remote power source co-act to provide an. additional means for control of main contactor 76.

In FIG. 4, power supply and signal generator 52, con nected to the output of bridge rectifiers 50b, produces at its output an analog signal proportional to the magnitude of the current sensed by

current monitors

44, 46 and 48. One output of generator 52 is connected to long delay pickup 54 which in a preferred embodiment, consists of a solid state time delay circuit. Another output of generator 52 is connected to the input of long delay pick up circuit 54. Pick up circuit 54 is also connected to long delay time circuit 58. The output of long delay time circuit 58 is connected to trip'circuit 60. An instantaneous trip circuit 56 is also provided having its input coupled to generator 52, and its output coupled to trip circuit 60.

In accordance with the standards set by the National Fire Protection Association (N.F.P.A.) for certifigal fire pumps, the instantaneous current applied to the pump motor is not to exceed 12 times normal, full load motor current. After a running time of between 14 to 19 seconds, the motor current should be below sit: times. normal, and after 40-60 seconds, the current should be below three times normal load.

'To comply with these standards, instantaneous trip circuit 56, includes on its input, a voltage divider, and a back-biased diode coupled to its output so that when [a signal from generator 52 representing a current greater than 12 times: normal is applied to the voltage divider, the diode will c o nduct and provide a signal to trip circuit 60 so as to open circuit breaker 34. Instani taneous trip circuit 56 operates independently of pick 58. Circuit 58 will then set up a current threshold level which'decreases from 12 times tothree times full load motor current, over a timeinterval of 40-60 seconds, as shown in FIGL3.

FIG. 3 shows a typical log. plot of current versus time where line 90 represents the current flow to the pump motor during a time interval. Line 90a has been set for 12 times rated current and will always trip the circuit breaker if the current ever exceeds that value during its operation. Line 90b'represents the transition between instantaneous trip 56 and long delay pickup 54 which is set between 12 times rated currentyto three times rated current for a period of about 40-60 seconds. Long delay time circuit 58 is preferably-constructed 'as a solid state time delay circuit which serves to decrease the motor current trip level over a time interval of about 40-60 seconds, as in FIG. 3. Circuit SS will decrease the breaker trip level so thatafter 6-8 seconds of'elapsed time, the trip or threshold currentwill be about nine times full load rating. To comply with the N.F.P.A. standards, the current trip level will decrease to about six times normal motor current between 14-19 seconds, and will reachthree times normal current in about 40-60 seconds. After 40-60 seconds, the trip level is maintained at' three times full load motor current. Undernormal motor operating conditions for non-fire pump use, the motor current should not exceed 1.25 timesfull load value for any extended time interval. However, for fire pump use, it is more'important to keep the motor and pump operating to maintain water pressure, so the standards require the motor circuit be capable of receiving up to three times its full load current during its operation without being disconnected. V

.To operate the tire pump control, isolating switch 74 and circuit breaker 34 are closed to connect power to main contactor 76 as shown in H6. 6. If the pressure at the output of pump 80 is below a present level, pres sure control 82 will produce a signal at the input of timer 84 so that power relay 86 will be energized. Relayv 86 will couple power to the solenoid of main contactor 76 to close the contactor and connect power to pump motor 78. When the pressure at the output of pump 80 rises to a level that is preset in pressure control 82, the control de-energizes timer 84, relay 86 and the solenoid. Thus, after a short time delay, contactor 76 opens to shut off motor 78. If there is a drop in fluid pressure at the pump output, due to the operation ofa sprinkler head the fire pump control system will automatically operate to maintain a preset pressure in the sprinkler system.

The fire pump control system may be manually operated such as for tests purposes by depressing start button 28 which is located on the front face of housing 10. Start button 30 will connect power to the solenoid of main contactor 76 in order to energize pump motor 78. The start button bypasses pressure control switch 82 so that the system can be left turned on if required. Pump 80 generally includes an internal fluid bypass so as to protect the pump from excessive pressures by allowing some of th output pressure to be fed back into the input if the pressure exceeds a present level. Where a plurality of fire pump control systems are used, the start and stop buttons may be remotely located on a main control panel in the basement of the building so that maintenance personnel can check a plurality of fire pump control systems located on different floors from a single control panel.

The fire pump control system also includes the emergency run handle 22 shown projecting through an opening on the front face-which mechanically urges the solenoid of main contactor 76 closed, so that the pump motor will remain permanently connected to circuit breaker 34 until the handle is returned to its of position.

When the pump motor is connected to the power source by any one of the three previously-mentioned steps, the current applied to the pump motor in each electrical phase is sensed by tripping system shown in detail in FlG. 4. Ina preferred embodiment of the invention, instantaneously trip 56 has been set to operate at 12 times the normal rate of current of pump motor 78 so that if the normally rated pump current in any of the three

power lines

38, 40 or 42 exceeds 12 times the current rating of the pump motor, instantaneous trip 56 will provide a signal to operate trip circuit and cause circuit breaker 34 to disconnect the pump motor from the power lines- Instantaneous trip 56 operates separately and independently from

delay circuits

54 and 58. While only one embodiment of the present invention has been shown and described it will be apparent to those skilled in the art that many changes and modifications may be made thereto without departing from the inventions spirit and scope.

What is claimed is:

1. A self-contained fire pump control apparatus connected across the power lines for providing power to a fire pump motor to maintain fluid pressure in a fireprotection system comprising in combination:

a housing containing the apparatus;

afirst manually operated circuit breaker serially coupled with the power lines for disconnecting power from the power lines; second circuit breaker means serially coupled to said 7 first circuit breaker means;

current responsive means coupled to the power lines and connected to said second circuit breaker means said current responsive means having a decreasing current threshold level in response to the start of the fire pump motor, the threshold level 7 being setat a large multiple ,ofthe fullload current of the motor and decreasing toseveral times its full load current to maintain fluid pressure for fire pro- 1 tection; v

' third circuit breaker means serially coupled between said second circuit breaker means and the fire pump motor; and

pressure detection the firepump for closing said third circuit bre'aker means to connect electrical power to the fire pump motor when the fluid pressure dropsbelow apredetermined pressure level. v

2. The apparatus as in claim 1 wherein said current responsive means comprises current monitor means coupled to the power lines, a static sensor having its input coupled] to the output of said. current monitor means coupled to the output of I means,a shunt trip solenoid coupled to the outputof said static sensor and mechanically connected to open said second'circuit breaker'means, said static sensor operating said shunt trip solenoid when the current in the'power line exceeds predetermined levels.

' 3. The apparatus as in claim 2 wherein said static sensor comprises an auxiliary transformer including rectitier bridges for stepping down and rectifyingthe current output of said current monitor 'means, a power supplyand signal generator coupled to the rectified output of said auxiliary transformer and rectifier bridges, trip means having an input coupled to the output of said signal generator and an output applied to said shunt trip solenoid so that when the current exceeds predetermined levels, said shunt trip solenoid will open said second current breaker means. I

4. The apparatus as in claim 3 wherein said trip means includes an instantaneous trip having its input coupled to the output of said power supply and signal generator and the output of said instantaneous trip coupled to said shunt trip solenoid, said trip being set at a first current threshold level so that when said level is exceeded, said shunt trip solenoid operates to open said second circuit breaker means. H

S. The apparatus as in claim 4 wherein said trip means includes a long delay time circuit having an input coupled to said power supply and generator and its output coupled to said shunt trip solenoid,.said delay time circuit having'a decreasing current threshold level from said first level to a second current level over a preset time' interval, said long delay time circuit operating said shunt trip solenoid when said decreasing current threshold level is exceeded.

6. The apparatus'as re'citedin claim 5 wherein said trip means further comprises a pick up circuit having its input coupled to said power supply and'generator and its output coupled to said long delay time circuit,

- said trip means operating said long delay time circuit mechanically connected to the power solenoid and extending to the front face of said housing to provide means to manually open and close the contacts of said main contactor.

9, The apparatus as in claim 8 wherein said pressure detection means further comprises a pressure control transducer having one end coupled to the output of at least one pump, a timer having an input coupled to the outputof said .transducer and including electrical averaging, means for time averaging the instantaneous pressure variations detected atleast one pump output, a

power. relay whose input is coupled with the output of said timer, theoutput of said power relay being coupled tothe power solenoid so that when the pump output pressure exceeds apredeterminedlevel for a predeterrninedtime, the signalfrom said transducer. averaged by said timer will drive said power relay to cause the power solenoid to open the circuit of said main contactor.

10. The apparatus as in claim 9 wherein said output responsive means further includes anemergency stop.

button serially connected with the power solenoid to open the circuit of said main contactor and an emergency start button serially connected between said stop button and the power solenoid to close the circuit of said main contactor.

11. The apparatus as in claim 1 wherein said second circuit breaker means includes a manually operated tripping switch extending through the front face of said housing and including mechanical means coupled with said second circuit breaker means for opening and closingthe latter means.

12. The apparatus as in claim 1 wherein said first circuit breaker means comprises an isolating switch that includes a circuit breaker for each phase of the power lines and having a-manually operated handle controlling the operation of said isolating switch, said handle extending through the front face of said housing.

13. The apparatus as recited in claim 4 wherein said first current threshold level is set at twelve times the full load capacity of themotor.

14. A self-contained fire pump control apparatus connected across'the power lines for providing power to a fire p'ump motor to maintain fluid pressure in a fire protection system comprising in combination:

a housing containing the apparatus;

a manually operated switch connected to the power lines;

a circuit breaker serially connected to the switch and including a current sensor having a current threshold level foropening the breaker which decreases from-twelve to three times the full load current of the pump motor after the motor is operated to maintain fluid pressure for tire protection;

nected to said circuit breaker and having its output for connection to the pump motor;

a pressure detector coupled to the output of the pumpfor closing the solenoid operatedmain contactor when the fluid pressure drops below a predetermined pressure level.

a solenoid operated main contactorserially con- Disclaimer 3,859,565.Lee A. Henm'ngsen, Erie, Pa. FIRE PUMP CONTROL APPA- RATUS. Patent dated J an. 7, 1975. Disclaimer filed Mar. 8, 1976, by the assignee, Fz'wetrol, Inc. Hereby enters this disclaimer to

claims

1, 2, 11, 12, and 14 of said patent.

[Ofiicial Gazette May 25, 1976.]

Disclaimer 3,859,565.Lee A. Henm'ngsen, Erie, Pa. FIRE PUMP CONTROL APPA- RATUS. Patent dated J an. 7, 1975. Disclaimer filed Mar. 8, 1976, by

the assignee, Firezfml, Inc.

Hereby enters this disclaimer to

claims

1, 2, 11, 12, and 14: 0

f said patent. [Oyficz'al Gazette May 2-5, 1976.]

Claims

1. A self-contained fire pump control apparatus connected across the power lines for providing power to a fire pump motor to maintain fluid pressure in a fire protection system comprising in combination: a housing containing the apparatus; a first manually operated circuit breaker serially coupled with the power lines for disconnecting power from the power lines; second circuit breaker means serially coupled to said first circuit breaker means; current responsive means coupled to the power lines and connected to said second circuit breaker means said current responsive means having a decreasing current threshold level in response to the start of the fire pump motor, the threshold level being set at a large multiple of the full load current of the motor and decreasing to several times its full load current to maintain fluid pressure for fire protection; third circuit breaker means serially coupled between said second circuit breaker means and the fire pump motor; and pressure detection means coupled to the output of the fire pump for closing said third circuit breaker means to connect electrical power to the fire pump motor when the fluid pressure drops below a predetermined pressure level.

2. The apparatus as in claim 1 wherein said current responsive means comprises current monitor means coupled to the power lines, a static sensor having its input coupled to the output of said current monitor means, a shunt trip solenoid coupled to the output of said static sensor and mechanically connected to open said second circuit breaker means, said static sensor operating said shunt trip solenoid when the current in the power line exceeds predetermined levels.

3. The apparatus as in claim 2 wherein said static sensor comprises an auxiliary transformer including rectifier bridges for stepping down and rectifying the current output of said current monitor means, a power supply and signal generator coupled to the rectified output of said auxiliary transformer and rectifier bridges, trip means having an input coupled to the output of said signal generator and an output applied to said shunt trip solenoid so that when the current exceeds predetermined levels, said shunt trip solenoid will open said second current breaker means.

4. The apparatus as in claim 3 wherein said trip means includes an instantaneous trip having its input coupled to the output of said power supply and signal generator and the output of said instantaneous trip coupled to said shunt trip solenoid, said trip being set at a first current threshold level so that when said level is exceeded, said shunt trip solenoid operates to open said second circuit breaker means.

5. The apparatus as in claim 4 wherein said trip means includes a long delay time circuit having an input coupled to said power supply and generator and its output coupled to said shunt trip solenoid, said delay time circuit having a decreasing current threshold level from said first level to a second current level over a preset time interval, said long delay time circuit operating said shunt trip solenoid when said decreasing current threshold level is exceeded.

6. The apparatus as recited in claim 5 wherein said trip means further comprises a pick up circuit having its input coupled to said power supply and generator and its output coupled to said long delay time circuit, said trip means operating said long delay time circuit when said second current level is exceeded.

7. The apparatus as in claim 3 wherein said third circuit breaker means comprises a main contactor that includes a power solenoid to open and close the circuit between at least one fire pump and said second circuit breaker means.

8. The apparatus as in claim 7 wherein said main contactor additionally comprises an emergency run handle mechanically connected to the power solenoid and extending to the front face of said housing to provide means to manually open and close the contacts of said main contactor.

9. The apparatus as in claim 8 wherein said pressure detection means further comprises a pressure control transducer having one end coupled to the output of at least one pump, a timer having an input coupled to the output of said transducer and including electrical averaging means for time averaging the instantaneous pressure variations detected at least one pump output, a power relay whose input is coupled with the output of said timer, the output of said power relay being coupled to the power solenoid so that when the pump output pressure exceeds a predetermined level for a predetermined time, the signal from said transducer, averaged by said timer will drive said power relay to cause the power solenoid to open the circuit of said main contactor.

10. The apparatus as in claim 9 wherein said output responsive means further includes an emergency stop button serially connected with the power solenoid to open the circuit of said main contactor and an emergency start button serially connected between said stop button and the power solenoid to close the circuit of said main contactor.

11. The apparatus as in claim 1 wherein said second circuit breaker means includes a manually operated tripping switch extending through the front face of said housing and including mechanical means coupled with said second circuit breaker means for opening and closing the latter means.

12. The apparatus as in claim 1 wherein said first circuit breaker means comprises an isolating switch that includes a circuit breaker for each phase of the power lines and having a manually operated handle controlling the operation of said isolating switch, said handle extending through the front face of said housing.

13. The apparatus as recited in claim 4 wherein said first current threshold level is set at twelve times the full load capacity of the motor.

14. A self-contained fire pump control apparatus connected across the power lines for providing power to a fire pump motor to maintain fluid pressure in a fire protection system comprising in combination: a housing containing the apparatus; a manually operated switch connected to the power lines; a circuit breaker serially connected to the switch and including a current sensor having a current threshold level for opening the breaker which decreases from twelve to three times the full load current of the pump motor after the motor is operated to maintain fluid pressure for fire protection; a solenoid operated main contactor serially connected to said circuit breaker and having its Output for connection to the pump motor; a pressure detector coupled to the output of the pump for closing the solenoid operated main contactor when the fluid pressure drops below a predetermined pressure level.