GDD Instrumentation TxIII User manual

IP Transmitter
Model TxIII
1800W-2400V-10A
Instruction Manual
1963 rue Frank-Carrel, suite 203
Québec (Qc) Canada G1N 2E6
Tel.: [phone]
E-Mail: [email protected]
Web site: www.gddinstruments.com

Instrumentation GDD 2023-07-17 Page 2
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Instrumentation GDD 2023-07-17 Page 3
TABLE OF CONTENTS
1. INTRODUCTION....................................................................................................................................... 17
2. SAFETY .................................................................................................................................................... 17
3. TRANSMITTER DESCRIPTION .......................................................................................................... 17
3.1 EQUIPMENT LIST................................................................................................................................................17
3.2 TRANSMITTER COMPONENTS................................................................................................................................17
3.2.1. Output Terminals................................................................................................................................. 17
3.2.2. Status LEDs.......................................................................................................................................... 17
3.2.3. Ohmmeter and Wattmeter Display ..................................................................................................... 17
3.2.4. Current Display.................................................................................................................................... 17
3.2.5. High Voltage Indicator......................................................................................................................... 17
3.2.6. Time Base / DC Selector (optional)...................................................................................................... 17
3.2.7. Power Cable......................................................................................................................................... 17
3.2.8. Master-Slave Interface ........................................................................................................................ 17
3.2.9. Vent Pipe ............................................................................................................................................. 17
3.2.10. Serial Number................................................................................................................................. 17
3.2.11. Warning LEDs.................................................................................................................................. 17
3.2.12. Power switch: ON (1.5x) / OFF / ON (1.0x) ..................................................................................... 17
3.2.13. Circuit Breaker ................................................................................................................................ 17
3.2.14. Cancel O.L.P. Switch (open loop protection) ................................................................................... 17
3.2.15. Turbo Switch ................................................................................................................................... 17
3.2.16. Voltage Selector.............................................................................................................................. 17
4. TRANSMITTER OPERATION ...................................................................................................................... 17
4.1 STEPS TO FOLLOW ..............................................................................................................................................17
4.2 OUTPUT POWER................................................................................................................................................ 17
5. MASTER / SLAVE MODE ........................................................................................................................... 17
6. TROUBLESHOOTING.......................................................................................................................... 17
7. TECHNICAL HELP...................................................................................................................................... 17
8. SPECIFICATIONS....................................................................................................................................... 17
9. GLOSSARY ................................................................................................................................................ 17

Instrumentation GDD 2023-07-17 Page 4
1. INTRODUCTION
The GDD TxIII transmitter is used for time-domain induced polarization survey. Its transmission
cycle is 2 seconds ON, 2 seconds OFF. Other timings are available upon request. It is sturdy and
can operate in extreme climatic conditions (40oC to 65oC).
The GDD Tx III transmitter can be powered directly from a 120 VAC power source (240 VAC
optional), such as a portable regulated generator. The TxIII transmits up to 10 A in a highly
conductive ground or sends up to 2400V in a resistive ground for a total power of 1800W.
Because of its power and light weight, the TxIII increases the average daily productivity of an IP
crew doing a dipole-dipole survey. For example, Géosig Inc., a Québec contractor, averages a
productivity of over 4 km a day for n=6, a=25 m, and a crew of 5 persons.
The GDD TxIII is easy to use and automatically stops within microseconds if a short circuit occurs
or if the circuit opens. There is also an emergency stop button that shuts down quickly all power
inside the transmitter. However and for user safety, we strongly recommend always wearing
electrically insulated shoes and gloves while operating the transmitter.
Safety Hints:
Wear electrically insulated shoes. They should be approved by certified
organization (CSA, ANSI) i.e. marked with the logo:
Wear electrically insulated gloves rated class 1 (7,5 kV).
2. SAFETY

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3. TRANSMITTER DESCRIPTION
3.1 Equipment list
When receiving a GDD 1800W-2400V-10A IP Transmitter, model TXIII, ensure that it contains the
following elements:
One (1) TxIII transmitter built in a transportation box from Pelican
One (1) instruction manual
One (1) GDD Safe operating procedures (SOP)
One (1) GDD blue carrying case.
Optional
2, 25 or 50 meter electrical extension cord
GDD Master-Slave yellow cable
Do not hesitate to communicate with Instrumentation GDD if needed.

Instrumentation GDD 2023-07-17 Page 6
3.2 Transmitter components
Figure 1: Control panel
1-
Output
Termin
als
2-
Status
LEDs
3-
Ohmmete
r /
Wattmete
r
Display
4-
Current
Display
5-
High
Voltag
e
Indica
tor
6- Time
Base / DC
Selector
Optional
7-
Power
Cable
8-
Master/Slav
e interface
9-
Vent
Pipe
10-
Serial
Numb
er
11-
Warning
LEDs
12- Power
switch: ON
(1.5x) / OFF /
ON (1.0x)
13-
Circuit
Breaker
14-
Cancel
Open
Loop
Switch
15-
Turbo
Switch
16-
Voltage
Selector
Switch

Instrumentation GDD 2023-07-17 Page 7
3.2.1. Output Terminals
This is where the electrodes are connected. Press the button over each terminal to insert wires.
Be careful, the terminals can reach up to 2400 V.
3.2.2. Status LEDs
The red lights indicate the following elements:
HIGH VOLTAGE: This LED turns ON and OFF to indicate the presence of high voltage on the output
terminals, allowing the operator to follow the TxIII transmission cycle.
MASTER: This LED lights up for two reasons: when the transmitter is in stand-alone or in MASTER
configuration.
SLAVE: This LED lights up when the transmitter is in SLAVE configuration.
TURBO: This LED turns on when the turbo mode is activated, that is to say when the output
voltage changes from 700 V/840 V to 1400 V/1680 V or from 1000 V/1200 V to 2000 V/2400 V.
The lighted 150, 350, 500, 700/1400 or 1000/2000 red LEDs indicate the rated voltage present at
the output while transmitting. These values increase 120 % when the selector is on the 1.5X
mode.
3.2.3. Ohmmeter and Wattmeter Display
GROUND RESISTANCE: It displays the ground resistance when the generator is plugged and the
transmitter is powered OFF. The value shown is the contact resistance in kilo-ohms (x1000 Ω).
OUTPUT POWER: When the transmitter is transmitting (power switch in mode 1.0x or 1.5x), the
output power expressed in Watt is indicated instead of the contact resistance.
3.2.4. Current Display
Displays the output current (in A) and refreshes this value four times per second. The first and
the last reading may overlap the off cycle and have to be rejected.
3.2.5. High Voltage Indicator
3.2.6. Time Base / DC Selector (optional)
There is one possible time base selector. This optional time base selector allows the following
modes: 1s, 2s, 4s, 8s. The DC option is also available, allowing the transmitter to work as a DC
voltage source. To do so, place the DC switch to the left and the transmitter will work in DC mode.
To select a different time base, place the DC switch to the right and select the desired time base by

Instrumentation GDD 2023-07-17 Page 8
turning the rotary.
3.2.7. Power Cable
The termination of the power cable can be plugged into any 120 VAC /60 Hz voltage source. The
rated input voltage can be modified upon request to 220-240 VAC / 50-60 Hz. Please check
transmitter’s nameplate for specificity.
3.2.8. Master-Slave Interface
The Maser-Slave interface allows to link two transmitters with a synchronization cable to
increase the total output power and the output voltage of the system.
3.2.9. Vent Pipe
There are two vent pipes on the control panel. The FAN warning light indicates if the fan is
running. Make sure that the airflow is not being obstructed by any object (e.g.: leaves, snow, etc.).
3.2.10. Serial Number
Each instrument has its own serial number to identify it.
3.2.11. Warning LEDs
The red lights indicate the following problems:
LOGIC FAIL: Caused by an internal electronic failure.
LEAKAGE: A synchronization trouble caused a leakage current.
OPEN LOOP: This alarm is triggered when there is infinite resistance between the two output
terminals (the circuit is open) or when the output current is less than 30 mA (highly resistive
ground).
OVER CURRENT: This alarm is triggered when the current limit is exceeded. The current limit is
set to 10 A in normal mode and 5 A in DC mode.
A.C. IN HIGH: High (≥ 290 VAC) or irregular voltage from the generator. An unregulated generator
can trigger this alarm. The power transformer may overheat.
A.C. IN LOW: Low (≤ 170 VAC) or irregular voltage from the generator. An unregulated generator
can trigger this alarm.
OVERHEATING: The internal temperature of the transmitter is too high (≥ 85°C). Leave the
transmitter in this state until the LED turns off to let it cool off.
FAN: The FAN indicator lights up when the fan is running. The fan starts automatically to cool

Instrumentation GDD 2023-07-17 Page 9
down the transmitter when the temperature inside the transmitter is higher than 65°C.
STOP TX: Indicates that the transmitter stopped transmitting. This LED lights up with the warning
LEDs.
POWER LIMIT: Indicates that the power limit has been exceeded. This limit is set to 1800W.
POWER ON: Indicates that the transmitter is powered on.
3.2.12. Power switch: ON (1.5x) / OFF / ON (1.0x)
There are two Power modes: 1.0x and 1.5x. When the 1.5x mode is selected, the output voltage
will be 120 % higher and the power 150% higher compared to the 1.0x mode.
3.2.13. Circuit Breaker
There is a built in circuit breaker to protect the instrument from overload.
3.2.14. Cancel O.L.P. Switch (open loop protection)
The GDD TxIII has an internal open loop protection circuit to prevent direct electric shock to the
operator. This protection is triggered when the electrodes are not connected to the output
terminals or when the current is less than 30 mA.
NOTE: If the ground has a very high resistivity, the open loop protection could disrupt the
transmission of signal. To temporarily cancel the O.L.P. turn the TxIII OFF, press and hold the
Cancel O.L.P. button and turn the TxIII ON.
3.2.15. Turbo Switch
All voltage scales above 1200 V can be set with the Turbo switch. This switch allows to reach the
1400 V/1680 V or 2000 V/2400 V scales while the voltage selector is on the 700 V/840 V or
1000 V/1200 V position.
NOTE: It may take up to 4 seconds before the Turbo turns ON or OFF.
3.2.16. Voltage Selector
To set the output voltage, press and turn this selector to the right position. Pressing down this
knob will stop the current transmission. The available output voltages are:
1.0x mode: 150 V, 350 V, 500 V, 700 V, 1000 V, 1400 V and 2000 V.
1.5x mode: 180 V, 420 V, 600 V, 840 V, 1200 V, 1680 V and 2400 V.

Instrumentation GDD 2023-07-17 Page 10
4. TRANSMITTER OPERATION
4.1 Steps to follow
Here are the basic steps for a stand-alone operation of the TxIII:
1. Make sure that the TxIII is turned OFF.
2. Drive the electrodes into the ground and connect them to the output terminals with
insulated wires.
3. Start the generator.
4. Put the voltage selector to the lowest voltage scale (150 V) and turn the transmitter
ON (1.0x).
5. Increase the output voltage to increase the output power. It is not necessary to turn off
the transmitter to change the voltage scale or select a different time base (optional).
The 1.5x ON mode allows reaching an intermediate output power. Note that the
transmitter will automatically stop if you try to transmit more than 1800W. In this case,
select a lower voltage scale and turn the transmitter OFF and ON again to reset the
STOP TX alarm.
IMPORTANT:
Turn the transmitter OFF only when the “HIGH VOLTAGE” LED is off, which occurs in the OFF
time of the cycle or when the STOP TX light is triggered.
Turn the transmitter OFF before shutting down the generator.
4.2 Output Power
If a generator more powerful than 1800W is used, the output power will be limited to 1800W
by the TxIII. If the generator used cannot deliver up to 1800W, such as a 700W generator, the
output power will be limited by the generator.