CA2010661C - Ground fault detector - Google Patents
Ground fault detectorInfo
- Publication number
- CA2010661C CA2010661C CA 2010661 CA2010661A CA2010661C CA 2010661 C CA2010661 C CA 2010661C CA 2010661 CA2010661 CA 2010661 CA 2010661 A CA2010661 A CA 2010661A CA 2010661 C CA2010661 C CA 2010661C
- Authority
- CA
- Canada
- Prior art keywords
- series
- ground fault
- relay
- normally
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000011664 signaling Effects 0.000 claims description 4
- 230000000007 visual effect Effects 0.000 abstract description 3
- 239000007788 liquid Substances 0.000 description 4
- 238000004880 explosion Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
- H02H5/10—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to mechanical injury, e.g. rupture of line, breakage of earth connection
- H02H5/105—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to mechanical injury, e.g. rupture of line, breakage of earth connection responsive to deterioration or interruption of earth connection
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
- H02H1/003—Fault detection by injection of an auxiliary voltage
Landscapes
- Emergency Protection Circuit Devices (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
ABSTRACT
A portable ground fault detector for use on tanker trucks to provide visual and audible warning of unsafe conditions. closing of a grounding circuit operating at low voltage permits energizing of a circuit to show safe grounding conditions and interruption of continuity of the grounding circuit provides visual and audible warning of unsafe conditions.
A portable ground fault detector for use on tanker trucks to provide visual and audible warning of unsafe conditions. closing of a grounding circuit operating at low voltage permits energizing of a circuit to show safe grounding conditions and interruption of continuity of the grounding circuit provides visual and audible warning of unsafe conditions.
Description
. ,. ~ .. -..
The invention relates to a ground fault detector and, more particularly, relates to a ground fault detector for use on tanker trucks.
The transfer of flammable liquids through non-electrical ~ ...., .;. .
conducting hose from and to tanker trucks has resulted in serious ~
. ,, explosions. It is believed that a charge of static electricity~;~
generated during the transfer operation creates a hot spark which ignites the flammable gases emitted by the said liquid. It is well known to electrically ground the tanker truck, the tank and related equipment receiving or providing the flammable liquid. However, a faulty ground such as an incomplete ground due to failure in;;~ ;
electrical continuity may remain undetected resulting in creation of the danger of an explosion. ~ `
U.S. Patent No. 3,290,668 discloses a grounding and indicating device operating from an AC power supply with a transformer to supply a weak current to a grounding circuit. Closing of the grounding circuit energizes a lamp - photoconductive cell combination which triggers a series of relays for actuating control .,: ,, and warning circuits. This device requires an AC power supply, which ~;
often is not available or convenient, poses a rlsk of sparking due to `~
the presence of the high voltage AC circuitry, and is expensive due to its complexity.
It is an object of the present invention to provide a small ~
and portable ground fault detector for use with tanker trucks .
transferring flammable liquids. It is desired that the ground fault detector be provided with audio and visual modes for reliable identificàtion of the lack or presence of electrical grounding and ;
for the instantaneous detection of a change in conditions during transfer.
:. '. ,i.' ' ....
. i. ~ .....
SUMMARY OF THE INVENTION 20106fi1 -. ,~ ,,~. i .
In its broad aspect, the ground fault detector of the .:;~
-,:
invention comprises a first grounding clamp and a relay electrically - .
connected in series to a battery power supply and a second grounding . ~.
clamp and a plurality of diodes electrically connected in series to said battery, to form a grounding circuit through an article to be grounded; said relay having switching means with normally - open and normally - closed contacts; a warning circuit electrically connected ~-~
in ~eries to the battery power supply through the normally - closed - ;
contact of the relay - actuated switching means having signalling means to warn of a ground fault condition; and a safe indicating ~ ~`
circuit electrically connected in series to the battery power supply : -through the normally - open contact of the relay - actuated switching means having signalling means to advise a grounded condition during -~
energization of the relay. ~:
The battery power supply preferably is comprised of a pair . ~
o~ low-voltage batteries, one of which is used to power warning and ;~` ;
safe indicating circuits in parallel with the grounding circuit.
~ , BRIEF DESCRIPTION OF THE DRAWING
,"',.',~': ' The present invention will be described with reference to ;-.-the attached drawing in which the circuit of the invention is shown ;`~
schematically. ;.
DESCRIPTION OF THE PREFERRED ENBODIMENT
:~..' :~', . ~
With reference to the drawing, a power supply comprised of a ~ .
20~066~
pair of 3-volt batteries lo, 12 in series is connected through relay 13 to ground clamp 14 on its positive side to form a grounding circuit 15 through single-pole single-throw main power off-on switch .. ~ .~ ., 16 and line 18 having diodes 20 in series to ground clamp 22. The use of four diodes 20 each having a 0.7 volt drop results in a total ~ -voltage drop of 2.8 volts with a net voltage across ground clamps 14, ~`~ t 22 of only (6 - 2.8) 3.2 volts to ensure a spark-free environment in ~;
the event a grounding clamp should be dislodged.
Closing of switch 16 with completion of the circuit between -the two ground clamps energizes relay 13 to actuate single pole -double throw switch 24 to close normally - open contact 26 of safe condition circuit 27 through lead 28 to the positive terminal of battery 12. Light emitting diodes (green) 30, 32 in parallel are connected to the positive terminal of battery 12 through switch contact 26 and to the negative terminal of battery 12 through line 34 `~;~
and line 37 having variable preset resistor 39 in series with main switch 16. Closing of switch 16 concurrent with the energizing of relay 13 results in a safe "grounding" condition through ground clamps 14, 22 by completion of the circuit and applies an electrical current to diodes 30, 32 which emits a green light to confirm continuity of the grounding circuit of the system.
A parallel warning circuit 35 comprises battery 12, normally ;
closed contact 42 of switch 24, diode 43 in series, light-emitting diodes (red) 44, 45 and alarm 46 in parallel, and lead 40 to main `
power switch 16. Interruption of ground continuity due to dislodgement of one or both of clamps 14, 22, breaking of line 18 or ; ~`
the like, will disrupt current flow to and de-energize relay 13 to open switch contact 26 and allow normally - closed contact 42 to close, thereby de-energizing light emitting diodes (green) 30, 32 and energizing light emitting diodes (red) 44, 45 and audible horn alarm ; ;
46 to warn of a faulty ground condition. -~;
The qround fault detector circuit of the present invention provides a number of advantages. The power supply comprised of two , ,. ,~
:~, " i~
201066~
batteries 10, 12 in series provides sufficient power at 6 volts to operate relay 13 while permitting the ground circuit voltage and amperage across clamps 14, 22 at about 3.2 volts and 50 milli-amps, to remain at a safe level which is sufficiently low to obviate a hot spark on opening or closing the grounding circuit. Disruption of the power supply to relay 13 by a ground fault results in energization of an audible signal alarm and a flashing red light emitting diode in parallel while maintenance of a properly grounded condition results in energization of two flashing green light emitting diodes in parallel. A power off condition would be indicated by the absence of lights and sound.
It will be understood, of coursej that modifications can be ;
made in the embodiments of the invention illustrated and described ~
herein without departing from the scope and purview of the invention ~-as defined by the appended claims. ~ -~.' ~;''' ''''~` ~
,~"'.
"
The invention relates to a ground fault detector and, more particularly, relates to a ground fault detector for use on tanker trucks.
The transfer of flammable liquids through non-electrical ~ ...., .;. .
conducting hose from and to tanker trucks has resulted in serious ~
. ,, explosions. It is believed that a charge of static electricity~;~
generated during the transfer operation creates a hot spark which ignites the flammable gases emitted by the said liquid. It is well known to electrically ground the tanker truck, the tank and related equipment receiving or providing the flammable liquid. However, a faulty ground such as an incomplete ground due to failure in;;~ ;
electrical continuity may remain undetected resulting in creation of the danger of an explosion. ~ `
U.S. Patent No. 3,290,668 discloses a grounding and indicating device operating from an AC power supply with a transformer to supply a weak current to a grounding circuit. Closing of the grounding circuit energizes a lamp - photoconductive cell combination which triggers a series of relays for actuating control .,: ,, and warning circuits. This device requires an AC power supply, which ~;
often is not available or convenient, poses a rlsk of sparking due to `~
the presence of the high voltage AC circuitry, and is expensive due to its complexity.
It is an object of the present invention to provide a small ~
and portable ground fault detector for use with tanker trucks .
transferring flammable liquids. It is desired that the ground fault detector be provided with audio and visual modes for reliable identificàtion of the lack or presence of electrical grounding and ;
for the instantaneous detection of a change in conditions during transfer.
:. '. ,i.' ' ....
. i. ~ .....
SUMMARY OF THE INVENTION 20106fi1 -. ,~ ,,~. i .
In its broad aspect, the ground fault detector of the .:;~
-,:
invention comprises a first grounding clamp and a relay electrically - .
connected in series to a battery power supply and a second grounding . ~.
clamp and a plurality of diodes electrically connected in series to said battery, to form a grounding circuit through an article to be grounded; said relay having switching means with normally - open and normally - closed contacts; a warning circuit electrically connected ~-~
in ~eries to the battery power supply through the normally - closed - ;
contact of the relay - actuated switching means having signalling means to warn of a ground fault condition; and a safe indicating ~ ~`
circuit electrically connected in series to the battery power supply : -through the normally - open contact of the relay - actuated switching means having signalling means to advise a grounded condition during -~
energization of the relay. ~:
The battery power supply preferably is comprised of a pair . ~
o~ low-voltage batteries, one of which is used to power warning and ;~` ;
safe indicating circuits in parallel with the grounding circuit.
~ , BRIEF DESCRIPTION OF THE DRAWING
,"',.',~': ' The present invention will be described with reference to ;-.-the attached drawing in which the circuit of the invention is shown ;`~
schematically. ;.
DESCRIPTION OF THE PREFERRED ENBODIMENT
:~..' :~', . ~
With reference to the drawing, a power supply comprised of a ~ .
20~066~
pair of 3-volt batteries lo, 12 in series is connected through relay 13 to ground clamp 14 on its positive side to form a grounding circuit 15 through single-pole single-throw main power off-on switch .. ~ .~ ., 16 and line 18 having diodes 20 in series to ground clamp 22. The use of four diodes 20 each having a 0.7 volt drop results in a total ~ -voltage drop of 2.8 volts with a net voltage across ground clamps 14, ~`~ t 22 of only (6 - 2.8) 3.2 volts to ensure a spark-free environment in ~;
the event a grounding clamp should be dislodged.
Closing of switch 16 with completion of the circuit between -the two ground clamps energizes relay 13 to actuate single pole -double throw switch 24 to close normally - open contact 26 of safe condition circuit 27 through lead 28 to the positive terminal of battery 12. Light emitting diodes (green) 30, 32 in parallel are connected to the positive terminal of battery 12 through switch contact 26 and to the negative terminal of battery 12 through line 34 `~;~
and line 37 having variable preset resistor 39 in series with main switch 16. Closing of switch 16 concurrent with the energizing of relay 13 results in a safe "grounding" condition through ground clamps 14, 22 by completion of the circuit and applies an electrical current to diodes 30, 32 which emits a green light to confirm continuity of the grounding circuit of the system.
A parallel warning circuit 35 comprises battery 12, normally ;
closed contact 42 of switch 24, diode 43 in series, light-emitting diodes (red) 44, 45 and alarm 46 in parallel, and lead 40 to main `
power switch 16. Interruption of ground continuity due to dislodgement of one or both of clamps 14, 22, breaking of line 18 or ; ~`
the like, will disrupt current flow to and de-energize relay 13 to open switch contact 26 and allow normally - closed contact 42 to close, thereby de-energizing light emitting diodes (green) 30, 32 and energizing light emitting diodes (red) 44, 45 and audible horn alarm ; ;
46 to warn of a faulty ground condition. -~;
The qround fault detector circuit of the present invention provides a number of advantages. The power supply comprised of two , ,. ,~
:~, " i~
201066~
batteries 10, 12 in series provides sufficient power at 6 volts to operate relay 13 while permitting the ground circuit voltage and amperage across clamps 14, 22 at about 3.2 volts and 50 milli-amps, to remain at a safe level which is sufficiently low to obviate a hot spark on opening or closing the grounding circuit. Disruption of the power supply to relay 13 by a ground fault results in energization of an audible signal alarm and a flashing red light emitting diode in parallel while maintenance of a properly grounded condition results in energization of two flashing green light emitting diodes in parallel. A power off condition would be indicated by the absence of lights and sound.
It will be understood, of coursej that modifications can be ;
made in the embodiments of the invention illustrated and described ~
herein without departing from the scope and purview of the invention ~-as defined by the appended claims. ~ -~.' ~;''' ''''~` ~
,~"'.
"
Claims (4)
1. A ground fault detecting device comprising, in combination, a first grounding clamp and a relay electrically connected in series to a battery power supply comprised of a pair of batteries in series and a second grounding clamp and a plurality of diodes electrically connected in series to said battery power supply, to form a grounding circuit through an article to be grounded;
said relay having double throw switching means with a normally-open contact and a normally-closed contact said switching means being electrically connected between said batteries;
a warning circuit electrically connected in series to the battery power supply through the normally-closed contact of the relay-actuated switching means having signalling means to warn of a ground fault condition; and a safe indicating circuit electrically connected in series to the battery power supply through the normally-open contact of the relay-actuated switching means having signalling means to advise a grounded condition during energization of the relay and closing of said normally-open contact.
said relay having double throw switching means with a normally-open contact and a normally-closed contact said switching means being electrically connected between said batteries;
a warning circuit electrically connected in series to the battery power supply through the normally-closed contact of the relay-actuated switching means having signalling means to warn of a ground fault condition; and a safe indicating circuit electrically connected in series to the battery power supply through the normally-open contact of the relay-actuated switching means having signalling means to advise a grounded condition during energization of the relay and closing of said normally-open contact.
2. A ground fault detecting device as claimed in claim 1 in which the safe indicating circuit has a pair of green light-emitting diodes in parallel.
3. A ground fault detecting device as claimed in claim 1 or 2 in which the warning circuit has a pair of red light emitting diodes and an audible alarm all connected in parallel with each other, and a diode in series with said red light emitting diodes and audible alarm.
4. A ground fault detecting device as claimed in claim 1 or 2 said warning and safe indicating circuits having a resistor in series to limit the current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2010661 CA2010661C (en) | 1990-02-22 | 1990-02-22 | Ground fault detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2010661 CA2010661C (en) | 1990-02-22 | 1990-02-22 | Ground fault detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2010661A1 CA2010661A1 (en) | 1991-08-22 |
| CA2010661C true CA2010661C (en) | 1994-07-05 |
Family
ID=4144361
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2010661 Expired - Fee Related CA2010661C (en) | 1990-02-22 | 1990-02-22 | Ground fault detector |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2010661C (en) |
-
1990
- 1990-02-22 CA CA 2010661 patent/CA2010661C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2010661A1 (en) | 1991-08-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |