Fault indicator tester with test bar and test chamber

A testing apparatus for testing a sample fault indicator (11) of the type which has a current sensor (15), an automatic reset, an inrush restraint feature, and an indicator display (13) that are widely used by electric utilities for fault location of overhead and underground distribution power circuits. The first objective of the testing apparatus is to test the predetermined current threshold level of the sample fault indicator (11) which is specified by the producer. It provides for the simulation of a fault current condition by means of a pulse driver circuit (99). The output response of properly working fault indicator (11) under this test will cause the indicator display (13) to register a fault state. The second object provided by this apparatus is to test the automatic resetting of the sample fault indicator (11). It provides for simulating a reset signal (105) for a controlled duration of time. A further objective is to test the inrush restraint feature by providing an inrush current simulation, a problem associated with reclosures on power circuits. Testing for inrush restrain shall verify that the sample fault indicator (11) can distinguish between fault currents and inrush currents, thereby preventing a false indication. The apparatus has a test bar (25) means of holding the sample fault indicator within a testing chamber (23) that is under test.

BACKGROUND OF INVENTION--FIELD OF INVENTION 
This invention relates to a testing method and apparatus for the testing of 
electrical fault indicators of electrical power circuits, especially fault 
indicators for high voltage electrical insulated and bare conductors. 
BACKGROUND OF INVENTION--DESCRIPTION OF THE BACKGROUND 
It is well known that fault indicators are designed to sense an abnormally 
high magnetic field surrounding a conductor; particularly, when produced 
by a fault current; after which the fault indicator will visually indicate 
the fault. To provide the greatest benefit, fault indicators must reliably 
indicate the fault current which has passed through the power circuit. 
Also, after the faulted circuit is repaired and the electrical power 
circuits are restored to normal, properly working automatic resetting 
fault indicators will cause the visual indicator to display normal. 
Generally, utilities specify an inrush restraint feature of the fault 
indicator to eliminate the event of a false indication from abnormal 
switching on the power system. 
Inrush currents may occur on the power circuits equipped with circuit 
breakers and reclosure execution, this false indication can confuse the 
effort in locating the fault. For proficiency, fault indicators are 
typically specified with this feature in order to distinguish fault 
currents from inrush currents on those circuits with reclosure action. 
U.S. Pat. No. 4,039,932 to Duckworth discloses an apparatus which tests the 
reaction-time of fault indicators relating to the time required to detect 
the current surge to the time in which the indicator is displayed. The 
apparatus implements an interval timer which monitors the time from the 
initiation of a testing pulse to the time in which an optical sensor 
detects a display change of the fault indicator. The testing apparatus was 
designed for fault indicators which applied a mechanical rotor responding 
to the magnetic field generated from the fault current. Modern fault 
indicator designs typically are comprised of magnetic reed switches and 
electronic circuitry which have eliminated the slow reaction time of their 
predecessors. Unfortunately, the Duckworth devise is limited today since 
electrical utilities call for testing those modern features which 
incorporate electronic circuitry. In addition, the Duckworth apparatus 
fails to incorporate a means of testing the automatic reset features and 
the inrush restraint options. 
U.S. Pat. No. 4,101,826 to Hortismann discloses a fault indicator including 
a reed relay and further discloses that this equipment can be tested by 
means of a permanent magnet. This provincial testing method employing a 
permanent magnet has been used to test the Hortismann and other fault 
indicators. When the operator places the permanent magnet near the fault 
indicator, the contacts of a typical magnetic reed switch closes. 
The permanent magnet method can never simulate actual fault conditions and 
is an extremely primitive method. This method obviously has no provisions 
for testing the inrush restraint option and reset features of fault 
indicators. 
Manually controlled testing techniques are used for testing fault 
indicators. The conventional approach using a high current test set, 
normally used for motor overload relays and circuit breakers, is connected 
to the fault indicator. The current is manually adjusted until a 
predetermined high current passes through the fault indicator. A 
determination of the magnitude of the current is necessary to trip the 
fault indicator so that it indicates the fault. This approach does not 
simulate actual faulted conditions. The static nature of the current can 
result in defective fault indicators passing this test and yet not be 
operating effectively during the transient fault condition. This approach 
obviously has no provisions for testing either the automatic reset feature 
or the inrush restraint option of fault indicators. 
What is required, therefore, is a method for testing fault indicators which 
simulates actual power circuit conditions as though the fault current has 
passed through the fault indicator. A further requirement is a method that 
simulates conditions that confirm the automatic resetting features of the 
indicator. An added criteria is a method to simulate actual conditions of 
inrush current, resulting from power reclosure apparatus, to validate the 
fault indicator inrush restrain option features. Therefore, what is needed 
is an apparatus for use in testing which incorporates all the methods 
above into a single device to completely verify the dependability of the 
fault indicator. 
Objects and Advantages 
Accordingly, besides the objects and advantages of the fault indicator 
tester described in our above patent, several objects and advantages of 
the patent invention are: 
a) to provide a fault indicator tester which shall provide a means to test 
the predetermined threshold value of the fault indicator. The outputs of 
the tester, which is a fault signal, can be described as a simulation of a 
faulted power circuit. The output response of a properly working fault 
indicator under test shall cause the indicator to display a "FAULT" state 
as though a faulted current has passed through it; 
b) to provide a fault indicator tester as a means to test the automatic 
reset feature. The reset signal outputs provided by the tester is a 
selection of the following: 120 volt and 240 volt, electric field voltage, 
or current; the selection of the tester reset signal output can depend on 
the users preference of the producers options. The output response of a 
properly working fault indicator under the automatic reset test shall 
cause the indicator to change its indicator display from a "FAULT" state 
to a "NORMAL" state as though the power circuit were returned to normal; 
c) to provide a fault indicator tester as a means to test an inrush 
restraint feature. The inrush signal outputs provided by the tester shall 
have a magnitude approximate to an inrush current in power circuits which 
have had circuit breaker and reclosure execution. The inrush restraint 
feature can distinguish the fault current from the inrush current. 
The output response of a properly working fault indicator with inrush 
restraint feature under test shall prevent the applied signal to display a 
"FAULT" state; 
d) to provide a fault indicator tester as a means to hold the fault 
indicator which is under test. A pulse conductor, a high voltage lead, and 
a current lead are connected to the test bar which has conductive sleeves 
encased in an elongated electrically insulated tube. The test bar is 
approximately the same size in diameter as a distribution cable; 
e) to provide a fault indicator tester a means to test multiple sample 
fault indicators under simultaneous testing. The elongated test bar shall 
be sufficiently long to accommodate multiple indicators, actual numbers 
can be dependent on the physical dimensions of the sample indicators under 
test. In addition, the tester shall be provided with multiple test bars, 
typically two test bars, to accommodate multiple rows of fault indicators. 
Further objects and advantages are to provide a fault indicator tester that 
is simple, dependable, and convenient to use in the field and that is 
inexpensive to manufacture. Furthermore, it shall incorporate all three 
testing methods into a single device to completely validate the fault 
indicators prior to the time of installation or periodically after 
installation as a routine maintenance test. Our invention will become 
apparent from a consideration of the drawings and ensuing description. 
Summary, Ramifications, and Scope 
Thus, the reader can see that the fault indicator tester, our invention, 
provides a portable and reliable, yet inexpensive apparatus that is simple 
and convenient to use by the utility lineman. 
While our above description contains many specificities, these should not 
be construed as limitations on the scope of the invention, but rather as 
an exemplification of one preferred embodiment thereof. It will be 
apparent to those skilled in the art that various modifications and 
variations can be made in the method of testing of fault indicators of the 
present invention without departing from the scope or spirit of the 
invention. Thus, it is intended that the present invention cover the 
modifications and variations of this invention provided they come within 
the scope of the appended claims and their equivalents. Furthermore, the 
fault indicator tester has the additional advantages in that: 
it permits an immediate change from relays and relay control logic to a 
microprocessor and microprocessor control logic; 
it allows the fault indicator tester to test radio fault circuit indicator 
which contain radio transmitter which confirms a fault indication to a 
radio receiver; 
it permits an attachment of an elbow connector such as manufactured by 
"Elestimold.TM." for a test point automatic reset feature; 
it permits a fourth testing method to verify the reset restraint option 
which prevents resetting on feedback voltages; 
it permits a settable or adjustable value for the current reset signal and 
the electric field reset signal; 
it allows the fault indicator tester to test fault counters; 
it permits a second or a multitude of pulse driver circuits for a cycle or 
a multi-cycle fault component. 
Accordingly, the scope of the invention should be determined not by the 
embodiments illustrated, but by the appended claims and their legal 
equivalents.

REFERENCE NUMERALS IN DRAWINGS 
______________________________________ 
11 sample fault indicator 
13 indicator display 
15 current sensor 
17 field sensor 
19 secondary sensor 
21 electronic circuitry 
23 testing chamber 
25 test bar 
27 power source 
29 safety fuse 
31 on-off switch 
33 stop push button 
35 start push button 
37 mode selector switch 
37a ganged mode selector switch 
39 first relay 
39a contact of first relay 
41 second relay 
41a contact of second relay 
41b contact of second relay 
43 third relay 
43a contact of third relay 
43b contact of third relay 
43c contact of third relay 
45 line lead 
47 neutral lead 
48 chassis ground 
49 one shot timer 
49a rotary selector switch 
49b operational terminal 
49c resetterminal 
49d output terminal 
51 inrush timer 
51a rotary selector switch 
51b on-delay contact 
53 high voltage transformer 
55 120 volt terminal post 
57 step-up transformer 
59 current transformer 
61 240 volt terminal post 
65 first resistor 
67 charging resistor 
69 second resistor 
71 third resistor 
73 first capacitor 
75 second capacitor 
77 third capacitor 
79 first diode 
81 second diode 
83 inductor 
85 silicon controlled rectifier 
87 "Zener" diode 
89 settable voltage source 
89a rotary selector switch 
91 current lead 
93 high voltage lead 
95 120 volt lead 
97 240 volt lead 
99 pulse dhver circuit 
101 pulse conductor 
103 fault signal 
105 reset signal 
107 inrush signal 
109 fault test position 
111 reset test position 
113 inrush test position 
115 pulse component 
117 reset component 
Tr reset time 
Ti inrush time 
119 hinged cover 
121 instrument case 
123 frame 
125 front panel 
127 first plastic tube 
131 first conductive sleeve 
133 second plastic tube 
135 second conductive sleeve 
______________________________________ 
Description FIGS. 1, 2, 3-A, 3-B, 3-C, 4, and 5 
In FIG. 1, there is shown a block diagram depiction of a fault indicator 
tester according to this invention that is simulating tests on a sample 
fault indicator 11. The description of the fault indicator tester refers 
to the single fault indicator as shown in FIG. 1. However, testing could 
comprise of multiple fault indicators 11 of the same specifications using 
a test bar 25 as described in more detail below. 
Consider FIG. 2, schematic diagram that illustrates one embodiment of the 
present invention that is well suited for testing fault indicators 11. A 
safety fuse 29 is connected to a power source 27 which supplies 120 volts 
at 60 hertz. The opposite end of safety fuse 29 is attached to an on-off 
switch 31. Then the opposite end of on-off switch 31 is joined to a line 
lead 45 which is the control source for the fault indicator tester. The 
opposite end of power source 27 signal path is connected to a neutral lead 
47 that supplies a common control path for the fault indicator tester. 
A start push button 35, normally opened, is connected to line lead 45 and 
the opposite end is connected to an operational terminal 49b of a one shot 
timer 49. A stop push button 33, which is normally closed, is joined to 
line lead 45 and the opposite end is attached to a reset terminal 49c. An 
output terminal 49d provides a signal path and is connected to a 
rotational contact terminal of a mode selector switch 37. A common 
terminal of one shot timer 49 is connected to neutral lead 47. The time 
duration function of one shot timer 49 is to be provided by a rotary 
selector switch 49a and is to be positioned for the timing control. 
Commonly, rotary selector switch 49a selects discrete resistive values 
that predetermine the time duration of the one shot timer. 
Description 
Furthermore, rotary selector switch 49a and one shot timer 49 provide for a 
reset time Tr of a reset component 117. Reset time Tr and reset component 
117 are shown in FIGS. 3-A, 3-B, and 3-C and described in more detail 
below. Typically, rotary selector switch 49a will be mounted on a control 
panel with other operational switches. Whereby, control leads from rotary 
selector switch 49a are connected to the proper input terminals of one 
shot timer 49. 
Mode selector switch 37 and a ganged mode selector switch 37a share a 
common mechanical shaft and have an electrical circuit of a double pole 
with three positions. Accordingly, switch 37 and 37a provides for control 
of the three testing modes. The three testing modes are: a reset test 
position 111 were the object is to apply a reset signal 105; a fault test 
position 109 were the object is to apply a fault signal 103; and, an 
inrush test position 113 were the object is to apply an inrush signal 107. 
The purpose of selector switch 37 and 37a is for the operator to select a 
testing mode and apply the selected test on the sample fault indicator. 
When mode selector switch 37 is placed in the reset test position, a signal 
flow path is provided to a third relay 43. By which third relay 43 is 
energized through the time control of the one shot timer. When third relay 
43 is on, a contact 43b, normally open, closes activating the circuitry 
for reset component 117. Contacts 43b is connected to line lead 45 and the 
opposite end is joined to: a primary connection of a high voltage 
transformer 53; a primary connection of a step-up transformer 57, a 
primary connection of a current transformer 59, and a 120 volt lead 95. A 
secondary terminal of high voltage transformer 53 becomes a signal source 
and is connected to a high voltage lead 93. 
The opposite ends of a primary coil and a secondary coil of high voltage 
transformer 53 and neutral lead 47 are joined. A secondary terminal of 
step-up transformer 57 becomes a signal source and is connected to a 240 
volt lead 97. The opposite ends of a primary coil and a secondary coil of 
step-up transformer 57 and neutral lead 47 are joined. Finally, a 
secondary terminal of current transformer 59 becomes a signal source and 
is connected to a current lead 91. The opposite ends of a primary coil and 
a secondary coil of current transformer 59 are joined to the neutral lead. 
These circuits are the sources of the reset component of the reset signal 
shown in detail in FIG. 3-A and its operation is described in more detail 
below. 
Ganged mode selector switch 37a and the reset test position 111 is shown in 
FIG. 2. A signal flow path is incomplete to a gate firing circuit of a 
silicon controlled rectifier 85. Accordingly, the reset signal does not 
provide for a pulse component 115 in this mode. 
Consider FIG. 2, when switch 37 is selected to fault test position 109 a 
signal flow path is provided to a second relay 41. Under which, relay 41 
is energized through the time control of the one shot timer. When second 
relay 41 is on, a contact 41a, normally open, closes thereby energizing 
third relay 43. By which normally open contact 43b closes, providing the 
signal path flow to the circuitry for reset component 117 which is 
required for fault signal 103. The circuitry for the reset component is 
described in more detail above. And, reset component 117 of the fault 
signal is illustrated in FIG. 3-B and its operation is explained below. 
FIG. 2 shows ganged mode selector switch 37a and fault test position 109. 
The signal path flow can be completed between the line lead and the gate 
electrode of the silicon controlled rectifier by closure of a contact 43c. 
The third relay is on and the normally closed contact 43c is opened. Third 
relay 43 is energized through the contact of fault test position 109 and 
by the time control of one shot timer. When one shot timer 49 ends its 
time function, relay 43 is denergized, closing contact 43c. The closure of 
contact 43c will instantaneously complete the firing signal circuit, and 
supply a turn on signal to the gate electrode of the silicon controlled 
rectifier. Details regarding the description of the preferred embodiments 
of the silicon controlled rectifier and the pulse driver circuit are more 
fully described next. It is also noted that when switch 37a is in the 
fault test position, it allows a signal flow path through contact 43c 
only. 
Consider FIG. 2, the pulse driver circuit schematic diagram illustrates one 
embodiment that is well suited for the present invention. The function of 
the pulse driver circuit is to provide pulse component 115 of fault signal 
103 that is shown in FIG. 3-B and its operation is described below. Pulse 
driver circuit 99 comprises of a contact 41b normally open connected to 
line lead 45. The opposite end of contact 41b is connected to a first 
input terminal of a settable voltage source 89. A second input terminal of 
settable voltage source 89 is connected to neutral lead 47. Settable 
voltage source 89 is a direct current regulated voltage source that is 
commonly used for a capacitor charging circuit. During the fault testing 
mode described above, second relay 41 is on. By closing contacts 41b, it 
provides a signal path to the input of settable voltage source 89. A 
charging resistor 67 is connected to a first positive output of the 
settable voltage source. 
And, the opposite end of charging resistor 67 is connected to: a first 
capacitor 73, a second diode 81, and an inductor 83. Settable voltage 
source 89 provides for the charging current path to first capacitor 73 
through charging resistor 67. First capacitor 73 and second diode 81 are 
connected in parallel and their opposite ends are connected to neutral 
lead 47. A second negative output of settable voltage source 89 is 
connected to a chassis ground 48. The opposite end of inductor 83 is 
connected to an anode electrode of silicon control rectifier 85. The 
opposite end of silicon controlled rectifier 85, a cathode electrode, is 
connected to a pulse conductor 101. Operation of the settable voltage 
source 89 is to be provided by a rotary selector switch 89a. Rotary 
selector switch 89a is to be selected for a voltage setting control that 
determines a magnitude of the pulse component of fault signal 103. 
Commonly, rotary selector switch 89a selects discrete resistive values 
that predetermine the voltage magnitude output of source 89 and therefore 
the control of the magnitude of the pulse component. Typically, switch 89a 
is mounted on the control panel with other operational switches, then 
control leads from switch 89a are connected to the proper input terminals 
of source 89. In addition to the above description, the second function of 
the pulse driver circuit is to provide the pulse component of the inrush 
signal. That is shown in FIG. 3-C and its description and operation is 
characterized below. 
The function of the gate circuitry shown in FIG. 2 is to initiate a firing 
signal to the gate electrode by which the silicon controlled rectifier 
turns on and becomes conductive. A first resistor 65 is connected to line 
lead 45 and the opposite end is connected in series with an anode 
electrode of a first diode 79. 
The opposite end of a cathode of first diode 79 is connected to a third 
capacitor 77, a cathode electrode of a "zener" diode 87, and a rotational 
contact terminal of switch 37a. The opposite ends of third capacitor 77 
and an anode of "zener" diode 87 are joined to chassis ground 48. On-delay 
contact 51b is connected to a stationary contact of inrush test position 
113. And, contact 43c is connected to a stationary contact of fault test 
position 109 as depicted on switch 37a of FIG. 2-B. The opposite ends of 
contact 43c and on-delay contact 51b are joined providing a signal flow 
path to a second capacitor 75 and a third resistor 71. The opposite end of 
third resistor 71 is connected to chassis ground 48. Opposite end of 
second capacitor 75 is joined to a second resistor 69 and the gate 
electrode of silicon controlled rectifier 85. Finally, the opposite end of 
second resistor 69 is connected to chassis ground 48. The first signal 
flow path is controlled by the selection of fault test position 109 and 
the closure of contact 43c. The second signal flow path is provided by the 
controls of inrush test position 113 selection and the delayed closure of 
on-delay contact 51b. The gate circuitry of the silicon controlled 
rectifier described above is one embodiment of the present invention that 
completes the task of providing for the firing signal to the gate 
electrode. 
Consider FIG. 2, when mode selector switch is placed in the inrush test 
position a signal flow path is provided to a first relay 39. Under which, 
relay 39 is energized through the time control of one shot timer 49. When 
relay 39 is on, a contact 39a that is normally open, closes energizing 
second relay 41. Normally open contact 41a closes; by which the third 
relay is sealed on through closed contact 41a. 
When relay 43 energizes, normally open contact 43b closes, thereby 
providing the signal flow path for the reset component circuitry which is 
required for the inrush signal. The circuitry for the reset component is 
described in detail above. 
A contact 43a, which is normally closed, is connected to the line lead and 
the opposite end is connected to a first terminal of an inrush timer 51. A 
common terminal of inrush timer 51 is connected to the neutral lead. 
Accordingly, normally closed contacts 43a opens and releases the time 
control of inrush timer 51. 
When the ganged mode selector switch is placed in the inrush test position 
113, a signal flow path can be completed by closure of on-delay contact 
51b between line lead 45 and the gate electrode of silicon controlled 
rectifier 85. Relay 39 is energized through the time control of one shot 
timer 49. When one shot timer 49 terminates its time function, relay 39 is 
denergized, opening contact 39a. The opening of contact 39a turns off 
second relay 41; then contact 41a will open which finally release relay 
43. Contact 43b, which provides a signal path flow to the reset circuitry, 
opens ending the reset component. The closure of contact 43a will activate 
the on-delay timer 51. By which, on-delay contact 51b will close after a 
duration of an inrush time Ti has been completed. At the end of this time 
function, inrush time Ti shall initiate the firing signal circuit, and 
supply a turn on signal to the gate electrode. The gate circuitry is 
explained above in more detail. The time duration control of inrush timer 
51 is to be provided by a rotary selector switch 51a. Rotary selector 
switch 51a and inrush timer 51 provides for controlled time duration 
before the initiation of pulse component 115. Inrush time Ti of pulse 
component 115 is shown in detail in FIG. 3-C and its operation is 
described below. 
Rotary selector switch 51a selects discrete resistive values that 
predetermine the on-delay of contact 51b. Typically, rotary selector 
switch 51a will be mounted on a control panel with other operational 
switches. By which control leads from rotary selector switch 51a are 
connected to the proper input terminals of inrush timer 51. 
The inventive features of the fault indicator tester are electrical in 
nature and the housing for the fault indicator tester is not dealt with in 
detail. Only in general, the housing for the fault indicator tester is a 
basic instrument case 121. FIG. 5 shows testing chamber 23 which consists 
of a frame 123 fabricated, preferably, from panel grade aluminum sheets. 
The inside dimensions of testing chamber 23 are typically 9 inches wide by 
11 inches deep by 8 inches high. The interior space that is created by the 
frame and the instrument case provides for the various electronic and 
control relay components. Whereby, the components are mounted to the 
outside frame of the testing chamber. The final assembly is fitted and 
fastened into the instrument case. The fault indicator tester shall 
include a front panel 125, preferably, panel grade aluminum sheet, which 
shall support various mode switches, push buttons, and operational 
switches. 
FIG. 5 shows a typical embodiment of testing chamber 23, test bars 25, a 
120 volt terminal post 55, and a 240 volt terminal post 61 that provide 
the testing space and components for applying a test or a series of tests 
to the sample fault indicator. By which indicator 11 is mounted and tested 
on test bar 25 within the chamber 23 of the fault indicator tester 
according to this invention. FIG. 5 shows two test bars 25 positioned 
inside the testing chamber 23. The test bars are mounted on frame 123 that 
form the sides of the testing chamber. 
Accordingly, a multitude of sample fault indicators 11 having the same 
specification can be tested. The 240 volt terminal post and 120 volt 
terminal post are mounted on the inside wall of the testing chamber 23. 
Whereby, terminal posts 55 and 61 are accessible for the attachment of a 
secondary sensor 19 from the sample indicator. A hinged cover 119 for the 
testing chamber 23 is, preferably, fabricated from transparent-rigid 
material such as plastic. Hinged cover 119 permits access to the chamber 
23 for installation and removal of indicator 11. The transparent guard 
allows the operator to observe and verify an indicator display 13 of the 
fault indicator during various testing modes. 
FIG. 4, a view with cross-section lines of test bar 25 shows a first 
plastic tube 127, typically five-eights to seven-eights of an inch 
diameter, elongated "PVC" tube that forms an outer structure. The test 
bar's diameter approximates that of a distribution cable to which fault 
indicators 11 are normally attached. Test bar 25 is positioned in testing 
chamber 23 and is about nine inches long which length allows mounting of 
multiple indicators 11. A first conductive sleeve 131, preferably composed 
of brass tubing, is fabricated to fit securely into the inside center 
space of first plastic tube 127. By this construction, the test bar will 
establish a symmetrical radial electric field to be sensed by the 
indicators under test. High voltage lead 93 that provides the high voltage 
reset component is joined to first conductive sleeve 131. A second plastic 
tube 133, preferably "PVC" tubing, is assembled to fit firmly into the 
inside center area of the first conductive sleeve 131. A second conductive 
sleeve 135, typically one-quarter of an inch copper tubing, will be fitted 
firmly into second plastic tube 133. 
Pulse conductor 101 is connected to second conductive sleeve 135 and the 
opposite end is joined to chassis ground 48. The test bar by this 
construction will establish a magnetic field from a pulse component that 
will have precise concentric field lines to be sensed by the mounted 
indicators. Finally, current lead 91, typically a 16-gauge wire with 
thermoplastic insulation, is positioned into the center space of second 
conductive sleeve 135. By this assembly, the test bar will establish the 
current reset component to be sensed by the mounted indicator. 
Operation-FIGS. 2, 3-A, 3-B, and 3-C 
Consider FIG. 2, a block diagram illustration of a sample fault indicator 
11. The fault indicator comprises of an indicator display 13, a current 
sensor 15, a field sensor 17, an electronic circuitry 21, and a secondary 
sensor 19. Typically, indicators 11 will display a normal state, by a 
letter "N" with a white or a black background. Then, indicators 11 will 
register a fault state, by displaying a letter "F" with a red or an orange 
color background or by displaying a flashing light. 
In FIG. 2, there is a depiction of the fault indicator with automatic 
resetting sensors. Commonly, automatic resetting sensors are available 
from one of four options from the producers; that is: secondary sensors 
19, shown with a "pig tail" lead, which detects 120 or 240 volts; field 
sensor 17 which detects the presents of a high voltage field, and, current 
sensor 15 which senses the presents of a minimum current. Generally, 
utilities specify an inrush restraint feature to the fault indicator. By 
which, electronic circuitry 21 eliminates the events of a false indication 
from abnormal reclosure operation on the power circuit. 
Operation 
For an operator to use the fault indicator tester, the tester should be 
placed on a flat, secure table. The operator should place an on-off switch 
31 in the off position; then preferably, a power line cord is used to 
connect the tester to a power source 27. The operator should proceed by 
opening a hinged cover 119 to a testing chamber 23 and mount the sample 
fault indicator on a test bar 25. Indicators 11 with secondary sensor 19 
are joined to the appropriate terminal post 55 or 61. After indicator 11 
is mounted, the hinged cover shall be closed. 
The energization of a line lead 45 is controlled by the operation of an 
on-off switch 31. The operation of the fault indicator tester is to be 
provided by a start push button 35, when push button 35 is closed by its 
depression, an one shot timer 49 begins its timing function. In the event, 
one wishes to stop or reset the operation, by depressing a stop push 
button 33 the circuit path is interrupted to one shot timer 49 and is 
reset. 
A reset signal 105 is shown in FIG. 3-A where reference numerals 91, 93, 
95, and 97 signal leads show a respective reset component 117. Four signal 
leads are required to synthesize a reset signal 105 because of the variety 
of the producers options. The user will predetermine the duration of a 
reset time Tr by positioning a rotary selector switch 49a to the specified 
value provided by the producer. Settable values of reset time Tr are 
typically: 30 seconds, 45 seconds, 1 minute, 3 minutes, 5 minutes, 10 
minutes, 15 minutes, 20 minutes, 30 minutes, 45 minutes, and 60 minutes. 
From the selection of reset signals and from the range of reset times Tr 
which are available on the fault indicator tester, the user can apply a 
specific reset test to a variety of fault indicators 11. 
To begin the reset test on the sample indicator, indicator display 13 
should be in the fault state. To register a fault state, the operator can 
apply the fault test which operation is described below. Indicator 11 is 
placed in testing chamber 23 and mounted on a test bar 25. The operator 
positions a mode selector switch 37 and a ganged mode selector switch 37a 
in a reset test position 111. And, selects reset time Tr by positioning 
rotary selector switch 49a. On-off switch 31 is placed in the "ON" 
position and the operator depresses start push button 35. The fault 
indicator tester initiates an output reset signal 105 that is sensed by 
the fault indicator. The response of a properly working unit under the 
reset test will cause the fault indicator to change its display from the 
fault state to the normal state. 
Consider FIG. 3-B that shows reference numerals 91, 93, 95, and 97 leads 
and their respective reset component 117 of a fault signal 103. 
Furthermore, the choice of the position of rotary selector switch 49a will 
predetermine the duration of reset time Tr. In addition, FIG. 3-B shows 
pulse conductor 101 and its respective pulse component 115 of the fault 
signal. The fault indicator tester provides for settable magnitudes of a 
pulse component 115 by the positioning of a rotary selector switch 89a. 
This selection will predetermine the current magnitude required to operate 
the threshold level of the fault indicator. Suited values of the current 
magnitude are typically selected from: 100 amperes, 200 amperes, 300 
amperes, 400 amperes, 500 amperes, 600 amperes, 700 amperes, 800 amperes, 
900 amperes, 1000 amperes, and 1200 amperes. 
To begin the fault test on the sample fault indicator, indicator display 13 
should be in the normal state. 
To register a normal state, the operator can apply the reset test which 
operation is described above. The fault indicator is placed in testing 
chamber 23 and mounted on the test bar. The operator positions switch 37 
and 37a in a fault test position 109 and selects reset time Tr by 
positioning rotary selector switch 49a. The user must then select the 
current magnitude by positioning switch 89a to the desired value. The 
on-off switch is placed in the "ON" position and the operator depresses 
start push button 35. The fault indicator tester initiates the output of 
the fault signal sensed by the fault indicator. The response of a properly 
working unit under the fault test will cause the fault indicator to change 
its display from the normal state to the fault state. 
An Inrush signal 107 is shown in FIG. 3-C where reference numerals 91, 93, 
95, and 97 leads and their respective reset component 117. Furthermore, 
the choice of the position of rotary selector switch 49a will predetermine 
the duration of reset time Tr. Also, FIG. 3-C illustrates pulse conductor 
101 and its respective pulse component 115 of the inrush signal. The fault 
indicator tester provides for settable magnitudes of the pulse component 
by the selection of switch 89a. The user will then predetermine the 
duration of an inrush time Ti by positioning a rotary selector switch 51a. 
Settable values of inrush time Ti are typically: 100 milliseconds, 200 
milliseconds, 300 milliseconds, 400 milliseconds, and 500 milliseconds. 
To begin the fault test on the sample fault indicator, indicator display 13 
should be in the normal state. To register a normal state, the operator 
can apply the reset test which operation is described above. The fault 
indicator is placed in testing chamber 23 and mounted on the test bar. 
The operator positions switch 37 and 37a in inrush test position 113 then 
selects reset time Tr by positioning rotary selector switch 49a. And, 
selects inrush time Ti by positioning rotary selector switch 51a. The user 
must then select the current magnitude by positioning switch 89a to the 
desired value. The on-off switch is placed in the "ON" position and the 
operator depresses start push button 35. The fault indicator tester 
initiates the output of inrush signal 107 that shall be sensed by the 
fault indicator. The response of a properly working unit under the inrush 
test will cause the fault indicator to remain in the normal state. 
Furthermore, a properly working fault indicator 11 that has an inrush 
restrain features will distinguish the fault current from the inrush 
magnetizing currents in a power circuit. 
It will be apparent to those skilled in the art that various modifications 
and variations can be made in the method of testing of fault indicators of 
the present invention without departing from the scope or spirit of the 
invention. Thus, it is intended that the present invention cover the 
modifications and variations of this invention provided they come within 
the scope of the appended claims and their equivalents.