Scully ST-47 Series User manual

Scully ST-47 Groundhog
Technical Manual
ST-47 Series Self-Proving Vehicle
Grounding Verication System
Scully Signal Company / Tel. [phone] / Fax. [phone] / 800 2 SCULLY (272 8559)
70 Industrial Way, Wilmington, MA 01887-3479, USA / [e-mail] /
MaxSafety®
SYSTEMS

ST-47 Groundhog - Technical Manual
Table of Contents
General 5.
1.1 Purpose of Equipment
1.2 ST-47 Normal Operation
Technical Specications & Approvals 9.
2.1 Input Power
2.2 Control Contact
2.3 Operating Temperature
2.4 FM Approval & FM Approval for Canada
Installation 10.
3.1 Enclosure
3.2 Physical Location
3.3 Electrical Installation
3.4 Ground Ball Installation- Stand Alone Applications
3.5 Ground Bolt Installation- Combined with Rack Monitor
Initial System Checkout 11.
4.1 General
4.2 Models Without Bypass Switch
4.3 Models With Bypass Switch
4.4 Models With Deadman Feature
Servicing The ST-47 12.
5.1 General
5.2 Replacing Indicator Lamps
5.3 Tools & Test Equipment Required for Servicing
5.4 Test Procedure 1- Wire-Through Applications Only
5.5 Test Procedure 2- Stand Alone Applications Only
5.6 Troubleshooting Models With Deadman Capability

ST-47 Groundhog - Technical Manual
Table of Contents
Diagram Appendix
6.1 DWG 61655 – Installation Drawing with Entity Parameters 17.
6.2 DWG 31412 – Outline Drawing – Control Unit Enclosure 18.
6.3 DWG 63039 – Outline Drawing – Sculcon Junction Box 19.
6.4 DWG 61441 – Wiring Diagram – Typical Loading Rack Control 20.
6.5 DWG 61345 – Principle of Overll Prevention & Grounding 21.
6.6 DWG 61346 – Grounding Protection for Product Loading & Ofoading 22.
6.7 DWG 61442 – Mounting Diagram – Control Unit & Junction Box 23.
6.8 DWG 61334 – Internal Wiring Diagram ST-47-EL 24.
6.9 DWG 61333 – Internal Wiring Diagram ST-47-ELK 25.
6.10 DWG 61331 – Internal Wiring Diagram ST-47-EL/D 26.
6.11 DWG 61332 – Internal Wiring Diagram ST-47-ELK/D 27.
6.12 DWG 61121 – Field Wiring Diagram ST-47-115/240 EL(K) 28.
6.13 DWG 61099 – Field Wiring Diagram ST-35/ST-47 29.
6.14 DWG 61098 – Field Wiring Diagram ST-15/ST-47 30.
6.15 DWG 61141 – Field Wiring Diagram ST-47-115 EL(K)D 31.
6.16 DWG 61168 – Field Wiring Diagram ST-15-ELK/D & ST-47 32.
6.17 DWG 61167 – Field Wiring Diagram ST-15-ELK/D & ST-47 33.
6.18 DWG 61169 – Field Wiring Diagram ST-35-ELK/D & ST-47 34.
6.19 DWG 61202 – Replacement Parts for ST-47-115 35.
6.20 DWG 61273 – Replacement Parts for ST-47-240 36.

Self-Proving Vehicle Grounding Verication System
General
Page 5.
1.1 Purpose Of Equipment
The ST-47 Groundhog is a line powered, Self- Proving, Vehicle Ground Verication System. It may
be used to insure a safe ground between a terminal loading rack and a tank vehicle which is in the
process of loading or unloading a hazardous product. The Groundhog system can be used in one
of three modes: 1.) Wire-Through, 2.) Stand -Alone, 3.) Non Self-Proving. Optional front cover
lamps indicate grounded (green lamp on) or non-grounded (red lamp on) status. Intrinsically safe
ground verication signals connect to TB2 terminals 2 (ground) and 3 (proving signal) in modes 1
and 2. Refer to Figure 1.2 for ST-47 Terminal Block (TB) locations.
1.1.1 Wire-Through Mode Description
In the Wire-Through conguration, the ST-47 control monitor is ideally mounted near a new, or
existing, Scully overll prevention monitor (see Appendix for appropriate interconnection wiring
diagram). When the two monitors are located in close proximity, vehicle drivers or loader personnel
can easily view the status lamps.
Two wires from the ST-47 I.S. terminals connect to the new, or existing, overll prevention cable
junction box. A single Scully Ground Bolt, mounted on a tank vehicle (or other container), serves as
the truck ground verication point. The system is self-proving when the overll prevention plug is
connected to the vehicle mounted Ground Bolt (P/N 08560) through socket pin no. 9.
A time-varying intrinsically safe voltage is sent out on ST-47 TB2 terminal 3. With the Scully overll
protection plug connected to the vehicle mounted overll system socket, a ground connection is
established through pin 10 of the socket to the chassis of the vehicle. The ground proving signal
enters the socket through pin 9. The Ground Bolt is required to complete the circuit in the ST-47
controller. The circuit is completed through pin 9, through the green wire, through the Ground Bolt,
to the chassis of the vehicle or equipment, through pin 10 and back to the ground connection, TB2
terminal, at the controller. If the control monitor senses a complete signal path, it will close its
“permissive” contact. The permissive contact is typically used to control a pump, valve, or input to
a Terminal Automation System or Programmable Logic Controller (PLC).
1.1.2 Stand Alone Mode Description
Used in the Stand-Alone mode, the ST-47 Groundhog is typically mounted near the terminal rack
equipment and hard wires to the Scully Model SC-47CC or SC-47CC/D cable junction box. The
cable junction box contains terminals connecting to a special snap-on plug using a 32 foot (ten
meter) coiled or a 20 foot (six meter) straight cable. A single Scully Ground Ball mounted on a tank
vehicle serves as the truck ground verication point. The system is self-proving when the snap-on
plug is connected to the vehicle mounted Ground Ball. When connected, the ST-47 sends a
time-varying intrinsically safe voltage from TB2 terminal 3 to the top of the two piece Ground Ball
and through the frame of the vehicle. The ball returns a portion of the signal to the control monitor
TB2 terminal 2 through its base. If the control monitor senses this signal, it will close its
“permissive” contact. The permissive contact is typically used to control a pump, valve, or input
to a Terminal Automation System.

ST-47 Groundhog - Technical Manual
General
Page 6.
1.1.3 Deadman Capable Model Description
(Applies to Models ST-47 EL(K)/D) Deadman capable models of the ST-47 differ from standard
models in two ways
1.) The Model ST-47/D requires the use of a Scully deadman equipped plug and cable or
ground ball connector and cable assemblies (Model SC-47CC/D). These include a
hand-operated deadman switch added to a standard plug and cable assembly.
Two additional wires must be run in the intrinsically Safe (I.S.) conduit which connects the
ST-47/D to the plug and cable assembly.
2.) Unlike the standard Model ST-47 there is no volt free permissive contact connected to
TB1 terminals 4 and 5. Only the permissive contact of TB1 terminal 5 can be utilized and it
must be connected to one wire (AC hot) of an inductive or resistive external device. The
other wire of the inductive or resistive external device is connected to AC neutral. In normal
operation, the deadman switch must be operated to “permit” operation of the external
device. When the ST-47 is permissive (green lamp lit), and the deadman switch is operated,
the external device connected to TB1 terminal 5 is energized.
1.2 ST-47 Normal Operation
1.2.1 Status Lamps
Match the state of the front cover indicators on the Groundhog with the chart below. Determine if
the status meets the conditions present and refer to the Troubleshooting Section of this manual if
required.
1.2.2 Use With Scully Ground Bolt or Ground Ball
A front panel mounted red lamp indicates that a safe ground attachment has not been made or,
the ST-47 is not connected to a vehicle. After connection to a vehicle mounted Ground Ball or
Ground Bolt the green lamp on the front panel illuminates indicating that the Scully Groundhog
system is operational and the ground path to the vehicle is complete. A normally open user contact
is provided on TB1 terminals 4 and 5, it should be connected to the permit circuitry at the terminal
loading rack. The permit contacts close when the ground path to the vehicle is veried.
GREEN
LAMP STATUS
RED INDICATION
OFF ON Rack to vehicle, rail tank car, container, etc. ground bond veried.
Output is “Permissive”
ON OFF Rack to vehicle, rail tank car, container, etc. ground bond not veried or unit is
malfunctioning. Output is “Non-Permissive”
OFF OFF 1.) Indicator lamp(s) is/are burned out.
2.) The unit is not powered.
3.) Optional Bypass switch is in OFF or BYPASS position.

Self-Proving Vehicle Grounding Verication System
General
Page 7.
1.2.3 Optional Bypass Switch-Models ST-47-115 or 240 ELK
An optional, three position switch, is mounted on the front cover. It allows the system to operate
normally in the AUTO (center position), turned OFF (left most position), or placed in BYPASS (right
most position). In the Bypass mode, the user contact will “permit” but, both the red and green
lamps will be extinguished.
1.2.4 Optional Deadman Capability-Models ST-47-115 or 240 EL(K)/D
1.2.4.1 Permissive Contact Connection to External Devices
Terminal 4 of TB1 is factory connected to the “hot” side of the AC power line. This factory installed
jumper connecting TB1 terminals 3 and 4 can be removed if the end-user must isolate the
permissive terminals. Do not exceed the following values for the permissive terminal input and
output.
Operating and Load Voltage Range..........95 to 135 VAC
Load Current Maximum............................5 Amperes resistive
If connection is made to an external device which is neither resistive nor inductive, an interposing
relay must be used. One example of this type of external device requiring an interposing relay is a
Programmable Logic Controller (PLC). When using a relay, connect one wire of the device to TB1
terminal 5 and the other wire to AC neutral. In most instances a normally open contact of the relay
is used. One “Common” contact should make connection to whatever voltage is required by the
device to be activated. When the ST-47 is permissive, the interposing relay will energize, and
operate an external device or devices.
1.2.4.2 Deadman Switch Connection to the ST-47
Two wires (black and white) are factory connected from the Deadman switch to terminals 1 and 2
inside the Scully plug and cable box. Applicable junction boxes may be identied by the “/D” in
their Model designation. The end-user must provide wiring which connects the two terminals to
TB3 inside (bottom) of the ST-47 explosion proof housing.
OFF AUTO BYPASS
Figure 1.1 Bypass Switch Illustration (Shown in AUTO Position)
WARNING
With the OFF/ AUTO/ BYPASS Switch in the BYPASS Position,
THERE IS NO GROUND VERIFICATION PROTECTION.

ST-47 Groundhog - Technical Manual
General
Page 8.
(TB1)
3
2
1
3
2
1
TB1
GND NEUT HOT
TB2
56
478 9
MAINS POWER FUSE
Size: 3AG
250 - 5A
“SLO - BLO”
CONTROL CONTACTS
RATED 5 AMPS
250 Volts MAX [ ]
Figure 1.2 ST-47 Terminal Block Location Illustration

Self-Proving Vehicle Grounding Verication System
Technical Specications and Approvals
Page 9.
2.1 Input Power
120 VAC +/- 15% or 208-240 VAC 50/60Hz
.25 Amps Maximum .125 Amps Maximum
2.2 Control Contact
Independently fused, 240 VAC
5 Amps resistive
2.3 Operating Temperature
-40 to +158 deg. F
(-40 to +70 deg. C)
2.4 FM Approval & FM Approval for Canada
This system’s outputs have been FM Approved as Intrinsically Safe for
Connection to Class I, Division 1, Groups C and D Hazardous Locations.
The Ground Ball or Ground Bolt may be mounted in a Class I, Division 1, Group C or D
Hazardous Location.
The ST-47-115 EL(K) and ST-47-240 EL(K) may be mounted in a Class I, Division 1, Group C or D
Hazardous Location.

ST-47 Groundhog - Technical Manual
Installation
Page 10.
3.1 Enclosure
The ST-47 is mounted in a NEMA 7 style explosion proof & weather proof enclosure that is typically
located near other rack equipment. Refer to typical loading rack installation for suggested
mounting.
3.2 Physical Location
a.) The front panel must be in the vertical position.
b.) The hinged front cover must be able to swing open for ease of servicing and chassis removal.
c.) The front panel indicators must be visible to the loader.
3.3 Electrical Installation
Systems using an ST-47 controller are wired as shown on an appropriate diagram in the appendix.
3.4 Ground Ball Installation - Stand Alone Applications
Refer to installations packed with Ground Ball, Scully Drawing No.61067.
3.5 Ground Bolt Installation - Combined with Rack Monitor
Refer to installations packed with Ground Bolt, Scully Drawing No.61081.
CAUTION
Keep the Intrinsically Safe Wiring SEPARATE from any Power
and Control Circuit Wiring by Running them in Separate Conduits.
No Wiring Should be Allowed to Pass Through from Top to Bottom
of the ST-47 Enclosure.

Self-Proving Vehicle Grounding Verication System
Initial System Checkout
Page 11.
4.1 General
(Refer to Figure 1.2 for Terminal Block & Fuse Locations)
Note: All Tests are done with line power applied to the ST-47.
4.2 Models Without Bypass Switch (ST-47- 115 or 240 EL)
Remove all wiring from the I.S. Terminal Strip TB2. You may check operation of the Groundhog by
physically shorting together terminals 1 and 2 on TB2 using a jumper wire. When this test is
performed, the Permit light should illuminate and Permit contacts (TB1 terminals 3 and 4) should
close. When the ST-47 is in the permissive mode any connected devices should activate. If the
connected device does not activate, consult the Troubleshooting section of this manual.
4.3 Models With Bypass Switch (ST-47- 115 or 240 ELK)
Place the Bypass switch in the AUTO position (center position). Remove all wiring from the I.S.
Terminal Strip TB2. You may check operation of the Groundhog by physically shorting together
intrinsically safe terminals 1 and 2 on TB2. When the test is performed, the permit light should
illuminate and the Permit contacts (TB1 terminals 4 and 5) should close. Place switch BYPASS
position (to the right). When the switch is in the Bypass position, power is removed from the ST-47
electronics and the front cover status lamps. Verify that the red and green status lamps are
extinguished and contacts TB1 terminals 4 and 5 are shorted. When the ST-47 is in the permissive
mode any connected devices should activate. If the connected device does not activate consult the
Troubleshooting section of this manual.
4.4 Models With Deadman Feature (ST-47- 115 or 240 EL(K)/D)
4.4.1 Models with Bypass Switch
To test the operation of the deadman switch, the ST-47 must be powered by the line voltage and
the Bypass switch in the AUTO position. When the ST-47 is not connected to a vehicle, rail car,
etc., the Red lamp on the front cover is lit. Connect the plug and cable or clamp to the vehicle to be
grounded. If the vehicle ground is veried the Green lamp on the front cover lights. If the Green
lamp does not light refer to previous sections 4.1 to 4.3.
Operate the deadman handle, the external device connected to the ST-47 permissive output will
activate. When the ST-47 is in the permissive mode any connected devices should activate. If the
connected device does not activate consult the Troubleshooting section of this manual.
4.4.2 Models without Bypass Switch
Perform the test as in paragraph 4.2 by applying power to the ST-47. Applying power is equivalent
to placing the Bypass switch in the AUTO position. When the ST-47 is in the permissive mode any
contact devices should activate. If the connected device does not activate consult the
Troubleshooting section of this manual.
CAUTION
Hazardous Voltages are Present Inside the ST-47 Explosion Proof
Housing. When Working Inside the ST-47 Enclosure Avoid Contact with
the TB1 Terminal Strip at the Top of the Housing

ST-47 Groundhog - Technical Manual
Servicing the ST-47
Page 12.
5.1 General
Unless noted otherwise, all the following Procedures are done with power applied to the ST-47. AC
power, as measured on the TB1 terminals 2 (neutral) and 3 hot) must be within the specied
tolerances. If it is not, correct the line voltage problems.
Returning part to Scully for repair or Warranty consideration: Before returning any defective
equipment to the Scully Signal Company for repair and/or Warranty consideration, call Scully at
1.800.272.8559 for an RMA (Return Material Authorization) number.
5.2 Replacing Indicator Lamps
5.2.1 Models with Bypass Switch
Turn off the power to the Groundhog by moving the switch to the far left position. Unscrew the lamp
lens, remove the defective bulb by unscrewing the lamp in the counter-clockwise direction. Insert a
new lamp by reversing the preceding procedure.
Current ST-47-115 models are shipped with LED xtures installed. There are seperate part
numbers for the green replacement LED (09385) and the red replacement LED (09384). Older
models using incandescent lamps can be upgraded by replacing the lamp assembly.
5.2.2 Models without Bypass Switch
Remove the line power from the Groundhog and replace the defective lamp using the procedure in
section 5.2.1.
5.3 Tools & Test Equipment Required for Servicing
5.3.1 Tools
a.) Good quality multi-meter
b.) Flat-blade screwdriver
c.) Two sets of Jumper wires with alligator clips at each end
5.3.2 Required Test Equipment for Wire-Through Mode Operation
Use appropriate equipment from the list below:
a.) Scully Universal Loading Rack Tester, ST-2-DSWJ
b.) Scully Ground Bolt (Part 08560) or Scully Ground Ball (Part 08274)
5.3.3 Required Test Equipment for Stand-Alone Mode Operation
a.) Scully Ground Bolt (Part 08560) or Scully Ground Ball (Part 08274)

Self-Proving Vehicle Grounding Verication System
Servicing the ST-47
Page 13.
5.4 Test Procedure 1 - Wire-Through Applications Only
Problem: The overll prevention plug is connected to the tanker mounted overll prevention system
and the RED non-permit lamp stays on. Unit does not “permit” externally connected devices.
Procedure 1, Step A
Does the tanker have a Scully Ground Bolt installed and wired to Pin 9 of the overll prevention
Socket?
Procedure 1, Step B
If you have a Scully Rack Tester, plug the overll prevention cable into the socket on the tester. If
you do not have a tester but do have a Scully Ground Bolt, use jumper wires to connect the green
wire on the bolt to Pin 9 of the plug and connect the body of the bolt to Pin 10
.
Does the ST-47 Permit?
Procedure 1, Step C
Using a Multi-Meter set on DC volts measure the voltage between Pin 9 (+) and Pin 10 (-) of the
overll prevention plug.
Is the voltage between 24 and 30 volts DC?
TIP
Overll Plug Pin Identication- Orient plug with pins facing you and the
molded-in arrow positioned at 12 o’clock, Pin 1 is located where the
arrow points. Count pins from Pin 1 in a clockwise direction. Pin 9 is in
the center on the left. Pin 10 is in the center on the right
NOYES
Go to the next step Install Ground Bolt on tanker (Scully Part# 08560)
NOYES
Trailer grounding system is at fault. Have
tanker owner check the installation or,
contact the Scully Service Department for
assistance.
Go to the next step
NOYES
Go to the next step Using an open end socket wrench, open the plug
and cable junction box. Remove line power to the
ST-47. Remove wires that come from the cable
and are connected to terminals 9 and 10. Power
the ST-47. Check the voltage at terminals 9 (+)
and 10 (-) on the terminal block found inside. If
you now read 24 and 30 VDC at terminals 9 and
10, there is a problem in the cable or wiring to the
ground ball plug. Correct the problem. If you still
get no voltage reading, go to the next step.

ST-47 Groundhog - Technical Manual
Servicing the ST-47
Page 14.
Procedure 1, Step D
Using the correct socket or hex wrench (Depends on ST-47 date of manufacture) remove the cover
fasteners and open the front cover. Using a at-blade screwdriver, remove the wires on intrinsically-
safe terminals TB2-2 and TB2-3. Using a Multi-Meter set on DC volts, measure the DC voltage
between terminals TB2-3 (+) and TB2-2 (-).
Is the voltage between 24 and 30 volts DC?
5.5 Test Procedure 2 - Stand-Alone Applications Only
Problem: The Ground Ball plug is connected to the tanker mounted Scully Ground Verication Ball
and RED non-permit lamp stays on. Unit does not “permit” externally connected devices.
Procedure 2, Step A
This step requires a Scully Ground Bolt or Ground Ball for testing- if you do not have one, Go to
Step A1. Use a jumper wire to connect the green wire on the bolt to the center pin inside of the plug
and connect the body of the bolt to one of the three tension ngers inside the plug. Does the
ST-47 Permit? If you have a Scully Ground Ball, attach the plug to it and touch the green wire to
exposed base of the Ground Ball.
Does the ST-47 Permit?
TIP
Ground Ball Connector Plug Maintenance
1.) Spring Finger Tension- Older styles of the Plug used an O-ring to tension the gripping
ngers which grip the base of the Ground Ball. The O-ring has been replaced by a new
tensioning ring (part# 31673) which provides a more positive grip.
2.) Contact Plunger Sticking- Severe weather conditions can cause the stainless steel
contact plunger (at the center, inside the plug) to stick in the down position. If it sticks it will
make a poor connection to the head of the Ground Ball. If it sticks, disassemble the plug and
apply white lube to the plunger where it contacts its plastic housing. To provide good contact
with the ball it must spring in and out freely.
NOYES
There is a wiring problem between the
ST-47 TB-2 terminals and the Junction Box
terminals. Correct the wiring problem
The ST-47 circuit module is defective. Replace
the module with a new one or, return the board
to the Scully Signal Company for repair or
Warranty consideration.
NOYES
Trailer grounding system is a fault. Have
tank owner check the installation or, contact
the Scull Service Department for assistance.
See TIP on Ground Ball Plug maintenance. If the
plug checks OK, go to procedure 2, Step A1.

Servicing the ST-47
Self-Proving Vehicle Grounding Verication System
Page 15.
Procedure 2, Step A1
(Ground Bolt or Ground Ball NOT required) If you do not have a Scully Ground Bolt or Ground Ball.
Using a Multi-Meter set on DC volts measure the voltage between spring plunger contact inside the
plug (+) and one of the three contact ngers (-) of the Ground Ball Connector Plug.
Is the voltage between 24 and 30 volts DC?
Procedure 2, Step B
(Ground Bolt required) Using the correct socket or hex wrench (depends on ST-47 date of
manufacture) remove the cover fasteners and open the front cover. Using a at-blade screwdriver,
remove the wires on intrinsically-safe terminals TB2 and 3. Attach the green wire of the Ground Bolt
to TB2-3 and the top of the bolt (at the end of the threads) to TB2-2.
Does the ST-47 Permit?
Procedure 2, Step B1
Using the correct socket or hex wrench (depends on ST-47 date of manufacture) remove the cover
fasteners and open the front cover. Using a at-blade screwdriver, remove the wires on
intrinsically-safe terminals TB2 and 3. Using a Multi-Meter set on DC volts, measure the DC voltage
between terminals TB2-3 (+) and TB2 (-).
Is the voltage between 24 and 30 volts DC?
NOYES
Trailer grounding system could be at fault.
Have tank owner check the installation or,
contact the Scully Service Department for
assistance.
If the voltage is lower or zero- Using an open
end socket wrench, open the plug and cable
junction box. Remove line power to the ST-47.
Remove wires that come from the cable and are
connected to terminals 9 and 10. Power the
ST-47. Check the voltage at terminals 9 (+) and
10 (-) at the terminal block found inside. Power
the ST-47. If you now read 24 and 30 VDC at
terminals 9 and 10. There is a problem in the
cable or wiring to the overll plug. Correct the
problem. If the voltage is still below limits, go to
step B1.
NOYES
There is a problem between the ST-47 TB-2
terminals and the Junction Box terminals.
Correct the wiring problem.
The ST-47 circuit module is defective. Replace
the module with a new one or, return the board
to the Scully Signal Company for repair or
Warranty consideration.
NOYES
There is a problem between the ST-47 TB-2
terminals and the Junction Box terminals.
Correct the wiring problem.
The ST-47 circuit module is defective. Replace
the module with a new one or, return the board
to the Scully Signal Company for repair or
Warranty consideration.

ST-47 Groundhog - Technical Manual
Servicing the ST-47
Page 16.
5.6 Troubleshooting Models with Deadman Capability
5.6.1 General
Before proceeding with this section the ST-47 must be operational. It must permit (green lamp)
when connected to a Scully Ground Ball or Ground Bolt. The unit is capable of turning on the green
permit lamp even if the deadman circuitry is not functioning properly. If the unit will not permit,
consult the earlier parts of this troubleshooting section for advice on repairing the problem.
5.6.2 Wire-Through and Stand-Alone Applications Troubleshooting
Problem: The ST-47 permit lamp comes on but the ST-47 will not activate an external device when
the deadman handle is operated. Turn off the power to the ST-47 by turning the Bypass switch to
the OFF position (if the unit has this option) or turn power off at the source. Using the correct
socket or hex wrench (depends on ST-47 date of manufacture) remove the cover fasteners and
open the front cover. Remove the fuse from its holder which is located at the right end of TB-1 by
turning the top on the right. Remove the now exposed glass fuse from the holder and check it with
a multi-meter set to the Ohms position. Do not rely on a visual inspection as a test for the fuse.
Is the fuse blown?
NOYES
The external device or wiring to it may be
shorted. Replace fuse, power-up system
and retest. If fuse continues to blow then
check for shorts in the output control wire to
device. Repair the problem, replace the fuse
with one that is the same rating and retest.
Replace the fuse in the holder and turn on the
power to the ST-47. With the cover of the ST-47
open, locate TB3 which is the two terminal strip
at the bottom of the explosion proof housing.
Using a jumper wire, short the two terminals
together. If the external device now operates.
There is a problem with the deadman switch or
the wiring to it. Repair the problem. If the ST-47
still does not permit, there could be a problem
with the I.S. Barrier relay that is located on the
inside front cover of unit. Consult the Scully
Service Department.

Self-Proving Vehicle Grounding Verication System
Diagram Appendix
Page 17.
6.1 DWG 61655 – Installation Drawing with Entity Parameters
61655 RevA
composants peuvent nuira a la securite intrinseque et creer des conditions dangereuses. Couper l'alimentation avant d'ouvrir la protection. Garder la courvercle clos tant que les
Disconnect power before opening enclosure. Keep cover tight while circuits are
Improper connections, component substitution or tampering may impair intrinsic
.
. .
alive. WARNING WARNING . safety and create hazardous conditions.
S/N
. .
'
Model: ST-47-
circuits sont en etat de marche.
Power Supply VAC, 20VA max.
AVERTISSEMENT
Um
'
YR
OPTIONAL INDICATORS & CONTROL
When system is in bypass both lamps will be out. Use care when bypassed.
SELF-PROVING VEHICLE GROUNDING SYSTEM
Scully Groundhog
AUTO
OFF
R
NONPERMISSIVE
CLASS I ZONE 1 GROUP IIB,T6, Ta=60°C, AEx[ia] IIB ENTITY 61655 (US) EXPLOSIONPROOF CLASS I DIVISION 1 GROUPS C & D,T6, Ta=60°C, AIS/I/1/CD/ENTITY-61655
G
BYPASS
PERMISSIVE
TM
CLASS I ZONE 1 PER CEC 18.100 (CAN)
USC
Approved
FM
(TB1)
3
2
1
3
2
1
(TB1)
(TB2)
56
478 9
ST-47-115 ST-47-240
OR
12345
3
2
1
GND FUSE
CONDUIT SEE NOTE 2
SEE NOTE 2 CONDUIT
ST-47-115-ELK ST-47-115-EL
EX-PROOF
5" X 10" X 5"
ST-47 MODEL: HOUSING: LIGHTS: BYPASS: POWER:
FEATURES:
YES YES YES
120 VAC
OR
240 VAC
NOTE: ALL MODELS ARE ALSO AVAILABLE WITH AN ST-47-240H MODULE,
IN THAT CASE, THE MODEL NUMBERWILL HAVE 240 SUBSTITUTED FOR 115.
1. NO REVISION TO DRAWING WITHOUT PRIOR FM APPROVAL.
4. CONTROL EQUIPMENT CONNECTED TO ASSOCIATED APPARATUS MUST NOT USE OR
NOTES:
TERMINAL Voc
PINS 3 TO 2
Isc MAXIMUM
PINS 2 TO 1
SCULLY GROUND BOLT
Voc = 29.6V Voc = 28.4V
POWER CAPACITANCE
ALLOWED
INDUCTANCE
ALLOWED
Isc = 0.4mA Isc = 14.2mA Po = 105mW
Po = 2.8mW
Ca = 0.070uF Ca = 0.079uF
La = 200mH La = 200mH
WARNING: SUBSTITUTION OF COMPONENTS MAY IMPAIR INTRINSIC SAFETY. WARNING:TO PREVENT IGNITION OF FLAMMABLE OR COMBUSTIBLE ATMOSPHERES, WARNING:TO PREVENT IGNITION OF FLAMMABLE OR COMBUSTIBLE ATMOSPHERES,
READ, UNDERSTAND AND ADHERE TO THE MANUFACTURE'S LIVE MAINTENANCE PROCEDURES.
ASSOCIATED APPARATUS WHEN THE FOLLOWING ISTRUE.
5. THE ENTITY CONCEPT ALLOWS INTERCONNECTION OF INTRINSICALLY SAFE APPARATUS WITH
GENERATE MORETHAN 250 VRMS OR VDC.
6. RESISTANCE BETWEEN INTRINSICALLY SAFE GROUND AND EARTH GROUND MUST BE LESS THAN 1.0 OHM.
DISCONNECT POWER BEFORE SERVICING.
7. INSTALLATION SHOULD BE IN ACCORDANCE WITH ANSI/ISA RP12.06.01 "INSTALLATION OF INTRINSICALLY
SAFE SYSTEMS FOR HAZARDOUS (CLASSIFIED) LOCATIONS" AND THE NATIONAL ELECTRICAL CODE. (ANSI/NFPA 70), OR FOR
8. THE OUTPUT ON THE ASSOCIATED APPARATUS IS NON-LINEAR.
Vmax or Ui > Voc, Vt or Uo
Imax or Ii > Isc, It or Io. Pmax or Pi > Po Ca > Ci + Ccable La > Li + Lcable
2. SEAL FITTINGS MUST BE INSTALLED WITHIN 18 INCHES OF AN EXPLOSION PROOF ENCLOSURE IN A HAZARDOUS LOCATION. 3. THE IMPORTANCE OF MAINTAINING ABSOLUTE SEPARATION BETWEEN INTRINSICALLY SAFE AND
NON-INTRINSICALLY SAFE WIRING CANNOT BE OVER EMPHASIZED!
OR
SCULLY GROUND BALL
(SIMPLE APPARATUS)
JUNCTION BOX
OPTIONAL OPTIONAL
PLUG & SOCKET
CLASS T, DIVISION 1, GROUPS C & D CLASS T, ZONE 0 AEx ia IIB HAZARDOUS LOCATION
JUNCTION BOX
OPTIONAL
PLUG & SOCKET
OPTIONAL
OR
GROUND CLAMP
RESISTOR
(SIMPLE APPARATUS)
OR
NOTE: I.S. OUTPUT PIN 2 IS TIED TO GND INTERNAL
TO THE MODULE.
DETAIL A
SCALE: 2X
JUNCTION BOX
OPTIONAL
3 2
2 3
1
2
1
2
1
CLASS T, ZONE 0 Ex ia IIB
HAZARDOUS LOCATION CLASS T ZONE 1 PER CEC 18.100 (CAN) CLASS T ZONE 1 GROUP IIB,T6, Ta=60°C, AEx[ia] IIB ENTITY 61655 (US) EXPLOSIONPROOF CLASS T DIVISION 1 GROUPS C & D, T6, Ta=60°C, AIS/I/1/CD/ENTITY-61655
"INSTALLATIONS IN CANADA PERTHE CANADIAN ELECTRIC CODE (C22.1)".
GND
NEUT
HOT
CONTROL CONTACTS
PWR
Scully Signal Company Wilmington, MA USA
MaxSafety® SYSTEMS

ST-47 Groundhog - Technical Manual
Diagram Appendix
Page 18.
31412 RevC
ENTRY
SAFE
INTRINSIC
scully
5.87
8.38
6.75
2.25 (57.1)
8.44
R
13.69
10°, 4 PL
G
SEE NOTE 2
2.00
6.62
ENCLOSURE EARTH
2.47
TOP VIEW
5.87
SEE NOTE 2
2. ENTRY HOLES:
1. DIMENSIONS ARE IN INCHES WITH MILLIMETERS
NOTES:
(347.7)
(214.3)
BOTTOM VIEW
FMC APPROVED MODELS: 3/4" NPT
ATEX APPROVED MODELS: M20 X 1.5
IN PARENTHIESS.
BONDING STUD
(168.1)
(50.8)
(149.0)
(62.7)
(12.7)
.50
FRONT VIEW
(212.9)
(149.0)
REAR VIEW
(146.0)
5.75
(171.5)
(MOUNTING LUG CENTERS)
(MOUNTING LUG CENTERS)
6.2 DWG 31412 – Outline Drawing – Control Unit Enclosure

Self-Proving Vehicle Grounding Verication System
Diagram Appendix
Page 19.
6.3 DWG 63039 – Outline Drawing – Sculcon Junction Box
63039 RevF
7.33
7.87
(200.0)
5 63 42
(186.2)
3.94
(100.0)
CONDUIT HUB (CABLE GLAND) Ø1.06 (27) KNOCKOUT FOR
1
3.94
(65.5)
2.58
(100.0)
(81.3)
3.20
1.44
(36.6)
Ø1.06 (27) HOLE FOR
CONDUIT HUB (CABLE GLAND)
MOUNTING CENTERS FOR #8 (4) HEX SOCKET HEAD SCREWS (4 PLACES)
NOTES:
1. DIMENSIONS ARE IN INCHES WITH
MILLIMETERS IN PARENTHIESS.

ST-47 Groundhog - Technical Manual
Diagram Appendix
Page 20.
6.4 DWG 61441 – Wiring Diagram – Typical Loading Rack Control
61441 RevB
4 5
TERMINALS
EMERGENCY
SHUTDOWN
SWITCH OR
RELAY SCULLY CONTROL UNIT'S
OUTPUT CONTACT
CARD READER
PERMISSIVE CONTACTS
SET-STOP METER
VALVE CONTROL
CONTACTS
LOADING VALVE
PILOT CONTROL
SOLENOIDS
SV SV
HI FLOW
LO FLOW
TO OTHER SET-STOP METERS ON SAME RACK
TO OTHER LOADING RACK
5A
HOT
NEUT
HI FLOW
LO FLOW
MAINS POWER
NOTE: WIRING SHOWN IS TYPICAL AND WILL VARY AS MORE OR LESS EQUIPMENT IS EMPLOYED. PUMP CONTROL CIRCUITS NOT SHOWN. THIS DIAGRAM IS INTENDED TO BE USED ONLY TO CLARIFY USE OF CONTROL CONTACTS. ALL CONTACTS SHOWN IN NON-PERMISSIVE STATES.
TYPICAL LOADING RACK CONTROL SHOWING PERMISSIVE CONTACTS
IN CIRCUIT TO LOADING VALVES.