Guildline 7520 Guide

OPERATION AND INSTRUCTION MANUAL
FOR
MODEL 7520
PRECISION VOLTAGE DIVIDER
www.guildline.com
NOTICE
The contents and information contained in this manual are proprietary to Guildline
Instruments Limited. They are to be used only as a guide to the operation and
maintenance of the equipment with which this manual was issued, and may not be
duplicated or transmitted by any means, either in whole or in part, without the written
permission of Guildline Instruments Limited.
OM7520-B-00
27 September, 2019

WARRANTY AND SERVICE
CERTIFICATION: Guildline Instruments Limited certifies that this product was tested
and inspected and found to meet its published specifications when it was shipped from
the factory.
WARRANTY: This product is warranted against defects in materials and workmanship
for a period of two years from date of shipment. During the warranty period, Guildline
Instruments Limited will, at its option, either repair or replace products that prove to be
defective.
SERVICE: For warranty service or repair, this product must be returned to the factory.
The buyer shall prepay shipping charges to Guildline Instruments Limited and Guildline
Instruments Limited shall pay surface shipping to the buyer. Permission must be
obtained from the factory for warranty repair returns.
LIMITATIONS: The foregoing warranty shall not apply to defects resulting from
improper or inadequate maintenance by the buyer, or unauthorized modifications or
misuse.
Neither Guildline Instruments Limited nor any of its employees shall be liable for any
direct or indirect, special, incidental or consequential damages arising out of the use of
this product.
No other warranty is expressed or implied.
SAFETY PRECAUTIONS
This product has been designed and tested in accordance with IEC1010-1/EN61010-1
including amendment 1(1995) for insulation category II use. Use of this equipment in a
manner not specified could result in personal injury.
AC POWER SOURCE: This product is intended to operate from an ac power source
that will apply not more than 264 V ac between either of the supply conductors and
ground.
POWER CORD: Use only the power cord and connector appropriate for the voltage
and plug configuration in your country. The cord must contain a safety ground conductor
and be connected to a plug that has a connection to earth ground. Use only a power cord
that is in good condition.
SIGNAL INPUT POWER: Signals applied to the input or output terminals must be
limited to levels deemed safe by the IEC/EN specifications. When applied voltages are
above 30 volts, the current source must limit the current to not more than 2 milliamps.

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TABLE OF CONTENTS
1. INTRODUCTION.................................................................................................. 1-1
1.1. DESCRIPTION.....................................................................................................................................1-1
1.2. WARRANTY.........................................................................................................................................1-1
1.3. TO OBTAIN WARRANTY SERVICE...............................................................................................1-3
1.4. SPECIFICATIONS...............................................................................................................................1-4
2. INSTALLATION ................................................................................................... 2-1
2.1. INITIAL INSPECTION .......................................................................................................................2-1
2.2. POWER REQUIREMENTS................................................................................................................2-1
2.3. LOCATION ...........................................................................................................................................2-1
2.4. WARM-UP AND SELF ALIGNMENT ..............................................................................................2-2
3. MANUAL OPERATION........................................................................................ 3-1
3.1. FRONT PANEL ....................................................................................................................................3-1
3.2. REAR PANEL.......................................................................................................................................3-2
3.3. FRONT PANEL OPERATION ...........................................................................................................3-3
3.4. TOUCH SCREEN DISPLAY FUNCTIONS ......................................................................................3-4
3.4.1. Opening Banner/Main Display Screen ...............................................................................................3-4
3.4.2. Divider Menu Screen..........................................................................................................................3-5
3.4.3. Comparator Menu Screen...................................................................................................................3-7
3.4.4. Setup Menu Screen.............................................................................................................................3-8
3.4.4.1. Self-Alignment Screen..............................................................................................................3-9
3.4.4.2. Password Screen .....................................................................................................................3-12
3.4.4.3. Offset Adjustment Screen .......................................................................................................3-13
3.4.4.4. System Parameters Screen ......................................................................................................3-15
3.4.5. Status Screen.....................................................................................................................................3-17
3.4.6. Log Screen........................................................................................................................................3-17
3.5. CONNECTION AND VOLTAGE DIVIDER INSTRUCTIONS....................................................3-18
3.6. 1:1 RATIO DIVIDER .........................................................................................................................3-18
3.7. 10:1 RATIO DIVIDER .......................................................................................................................3-19
3.8. 100:1 RATIO DIVIDER .....................................................................................................................3-19

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3.9. 1000:1 RATIO DIVIDER ...................................................................................................................3-19
3.10. CONNECTION AND VOLTAGE COMPARISON INSTRUCTIONS .........................................3-20
3.11. 0.01 VOLT, 1:1000 RATIO COMPARISON....................................................................................3-21
3.12. 0.1 VOLT, 1:100 RATIO COMPARISON........................................................................................3-21
3.13. 1 VOLT, 1:10 RATIO COMPARISON.............................................................................................3-21
3.14. 10 VOLT, 1:1 RATIO COMPARISON.............................................................................................3-22
3.15. 100 VOLT, 10:1 RATIO COMPARISON.........................................................................................3-22
3.16. 1000 VOLT, 100:1 RATIO COMPARISON.....................................................................................3-22
4. THEORY OF OPERATION................................................................................... 4-1
4.1. INTRODUCTION.................................................................................................................................4-1
4.2. LOW THERMAL DESIGN .................................................................................................................4-1
4.3. INTERNAL CIRCUITS .......................................................................................................................4-2
4.4. CIRCUIT PROTECTION....................................................................................................................4-2
4.5. COMPARISON MEASUREMENT CONFIGURATIONS...............................................................4-3
4.6. MEASUREMENT CONFIGURATION A: 0.01 VOLT COMPARISON ......................................4-4
4.7. MEASUREMENT CONFIGURATION B: 0.1 VOLT COMPARISON.........................................4-4
4.8. MEASUREMENT CONFIGURATION C: 1 VOLT COMPARISON ...........................................4-4
4.9. MEASUREMENT CONFIGURATION D: 10 VOLT COMPARISON .........................................4-4
4.10. MEASUREMENT CONFIGURATION E: 100 VOLT COMPARISON........................................4-5
4.11. MEASUREMENT CONFIGURATION F: 1000 VOLT COMPARISON......................................4-5
4.12. INTERNAL RATIO ALIGNMENT....................................................................................................4-5
5. MAINTENANCE AND TROUBLE SHOOTING.................................................... 5-1
5.1. PERIODIC MAINTENANCE .............................................................................................................5-1
5.2. UNSTABLE READINGS .....................................................................................................................5-1
5.3. ALIGNMENT........................................................................................................................................5-1
5.4. SERVICE...............................................................................................................................................5-1

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6. REMOTE CONTROL............................................................................................ 6-1
6.1. REMOTE OPERATION......................................................................................................................6-1
6.2. REMOTE COMMANDS......................................................................................................................6-2

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LIST OF FIGURES
FIGURE 1-1: GUILDLINE MODEL 7520 PRECISION VOLTAGE DIVIDER.............................................1-1
FIGURE 3-1: FRONT PANEL GUILDLINE MODEL 7520..............................................................................3-1
FIGURE 3-2: REAR PANEL GUILDLINE MODEL 7520.................................................................................3-2
FIGURE 3-3: GUILDLINE MODEL 7520 MENU/SCREEN HIERARCHY ...................................................3-3
FIGURE 3-4: MODEL 7520 CONNECTIONS FOR OPERATION AS A VOLTAGE DIVIDER...............3-18
FIGURE 3-5: MODEL 7520 CONNECTIONS FOR COMPARISONS UUT TO 10 VOLTS.......................3-20
FIGURE 4-1: 7520 COMPARISON MEASUREMENT CONFIGURATIONS................................................4-3

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1. INTRODUCTION
1.1. DESCRIPTION
The Guildline Precision Voltage Divider, with extremely low thermal offsets and built-in
temperature controlled chamber, is ideal for voltage ratio measurements to sub-ppm
accuracy. Input voltages in the range of 10 mV to 1100 V can be divided by ratios of
1:1000, 1:100, 1:10, 1:1, 10:1, and 100:1 with accuracies of 0.5, 0.2, 0.1, 0.05, 0.1, and
0.2 µV/V respectively.
Special care has been taken to minimize thermal offsets and noise. The switches used are
high isolation, low thermal relays. The 7520 can be operated from the front panel touch
screen or by SCPI commands sent over the USB or IEEE Interfaces.
Figure 1-1: Guildline Model 7520 Precision Voltage Divider
The voltage divider is fully controlled by an internal micro-processor through a front
panel touch screen.
1.2. WARRANTY
Each Model 7520 Precision Voltage Divider provided includes a two (2) year warranty in
which Guildline Instruments warrants that the unit is free from defects in material,
workmanship, manufacturing, and design and will perform to or exceed specifications, if
operated properly, for the duration of the two (2) year warranty coverage. This warranty
only extends to the intended original purchaser.

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Guildline will repair or replace any failed unit at no additional cost to the customer.
Guildline will be responsible for returning warranty standards to the owner and will bear
transportation costs from the repair center back to the user. It will be the customer’s
responsibility for transportation costs for equipment returned to Guildline for repair or
replacement. Warranty repairs will be provided in Canada.
Guildline does not provide warranty service or file claims due to shipping damage.
Customers are responsible for properly packaging instruments and insuring
instruments, to account for the possibility of shipping damage.
These warranties will not, in any way, be voided by any customer performed routine
maintenance accomplished in accordance with Guildline's service procedures (e.g.
replace fuses, adjust instrument in accordance with calibration instructions, lubrication,
cleaning, etc.).

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1.3. TO OBTAIN WARRANTY SERVICE
Before returning any warranty equipment to Guildline Service Center, a Return
Authorization Number (RMA) and shipping instructions from Guildline Instruments is
required. Guildline Service Center information is as follows:
The phone number in the USA and Canada to obtain Product Support, Calibration Service or
Replacment Parts is [phone].
To Contact Guildline Instruments, the following information is provided.
USA and Canada Telephone: [phone]
USA and Canada Fax: [phone]
Outside US and Canada Telephone: + [0] [1] 613 283-3000
Outside US and Canada Fax: + [0] [1] 613 283-6082
You can also contact Guildline Instruments Limted via their Email or Website.
Email is: [e-mail]
Website is: www.guildline.com

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1.4. SPECIFICATIONS
VOLTAGE DIVIDER RATIO SELECTIONS
1:1000, 1:100, 1:10, 1:1, 10:1, and 100:1
VOLTAGE DIVIDER RATIO UNCERTANTIES
1 –Relative to Reference Standard used.
2 –After Self-Alignment or within 140 hours from last Self-Alignment.
3 –Applies to Both the Divider Chain and Driven Guard.
7520 SPECIFICATI O NS
Voltage Divider Ratio
Voltage Divider Ratios Output Uncertainty 1,2
1:1
0.05
10:1
0.1
100:1
0.2
1000:1
0.5
Maximum Voltages
Voltage Input Terminals
1100 Vdc
Reference Standard Terminals
12.5 Vdc
Resistance
Ratios
Input3
Output
1:1 ratio
direct connection to input
10:1 ratio
2.303 MΩ
270 kΩ
100:1 ratio
2.303 MΩ
43.2 kΩ
1000:1 ratio
2.303 MΩ
5.8 kΩ
Communication
USB, IEEE 488.2, SCPI Based Language Instructions
Environmental
Operating
Storage
Temperature
+21 °C to +25 °C (69.8 °F to 77
°F)
-20 °C to +60 °C (-4 °F to 140 °F)
Humidity
20 % to 50 % RH
15 % to 80 % RH (Non-Condensing)
Power Requirements
VAC: 100 V to 240 V ± 10 % / 50 or 60 Hz ± 5 %, 60 VA
Dimensions (Length x Width x Height)
Weight
503 mm x 455 mm x 133 mm
19.8” x 17.7” x 5.2”
11 kg
24 lbs

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INPUT VOLTAGE RANGE
0.01 volts to 1100 volts
NOMINAL OUPUT VOLTAGES
0.01, 0.1, 1.0, 10, 100, and 1000 volts
ENVIRONMENTAL LIMITS
Operating: 19.5 oC to 26.1 oC and 20 % to 50 % relative humidity
Storage: -20 oC to 70 oC and 15 % to 80 % relative humidity
POWER COEFFICIENT EFFECTS ON RATIO ACCURACY
< 0.015 ppm/V
ALTITUDE EFFECTS
Not Applicable if Self-Alignment Process is run at the same altitude as the ratio
measurements. Any altitude effects will be compensated for by the Self-Alignment
Process.
DIVIDER RESISTANCE
Divider 3.0 MΩ ± 0.1 %
Driven guard 10.0 MΩ ± 0.1 %
INPUT RESISTANCE (no load on ref or output)
1:1 ratio Short
10:1 ratio 2.3 MΩ ± 0.1 %
100:1 ratio 2.3 MΩ ± 0.1 %
1000:1 ratio 2.3 MΩ ± 0.1 %
OUTPUT RESISTANCE (no load on ref or input)
1:1 ratio 0 Ω ± 0.1 %
1:10 ratio 270 kΩ ± 0.1 %
1:100 ratio 43.2 kΩ ± 0.1 %
1:1000 ratio 5.8 kΩ ± 0.1 %
SIZE
L x W x H: 503 mm (19.8 in.) x 450 mm (17.7 in.) x 133 mm (5.2 in.)

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WEIGHT
11 kg (24 lb.)
LINE POWER
100 V –240 V ±10 %
45 Hz to 66 Hz
60 VA

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2. INSTALLATION
2.1. INITIAL INSPECTION
This instrument was carefully inspected both mechanically and electrically before
shipment. It should be free of marks and scratches and in perfect electrical order upon
receipt.
Unpack the instrument and retain the shipping container until the instrument has been
inspected for damage in shipment. If in-shipment damage is observed, notify the carrier
and obtain authorization for repairs before returning the instrument to the factory.
2.2. POWER REQUIREMENTS
The instrument is shipped with a three-wire line cord and must be connected to a
grounded 50 to 60 Hz ac power source. This product will operate at between 100 V and
240 V all ±10 %.
WARNING: BEFORE SWITCHING ON THIS INSTRUMENT, THE
PROTECTIVE TERMINAL OF THIS INSTRUMENT MUST BE CONNECTED
TO A PROTECTIVE EARTH CONTACT. THE POWER LINE CORD
SUPPLIED WILL PROVIDE THE PROTECTIVE GROUNDING WHEN
INSERTED INTO A SOCKET OUTLET PROVIDED WITH AN EARTH
CONTACT. THE PROTECTIVE ACTION MUST NOT BE NEGATED BY THE
USE OF AN EXTENSION CORD OR ADAPTOR WITHOUT A PROTECTIVE
GROUNDING CONDUCTOR.
2.3. LOCATION
To ensure optimum performance, the Precision Voltage Divider should be installed in an
area having reasonably constant temperature, no strong electrostatic or magnetic fields,
and a minimum amount of vibration. The unit should not be located near heating or
cooling vents or in direct sunlight. Such locations can cause sudden temperature changes
resulting in generation of errors in the measurements due to thermal effects.
WARNING: NEVER CHANGE OR ENGAGE A VOTAGE DIVIDER MODE OF
OPERATION WHILE LIVE VOLTAGE IS PRESENT. DOING SO CAN
DAMAGE THE VOLTAGE DIVIDER, OTHER CONNECTED EQUIPMENT
AND POSSIBLY RESULT IN INJURY OR DEATH. THE VOLTAGE DIVIDE
CAN BE OPERATED UP TO 1100V AND THEREFORE LEATHAL VOLTAGES
MAY BE PRESENT ON INPUT TERMINALS OR EVEN OUTPUT TERMINALS
IF USED INCORRECTLY.

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2.4. WARM-UP AND SELF ALIGNMENT
When the 7520 is first powered up a red screen will appear during an initialization phase
which takes about 20 seconds. Following successful initialization, you will be greeted by
the main screen, the heaters will be automatically turned ON and the status bar at the
bottom of all screens will show “Warming up”. The warming up process takes about 6
hours and varies slightly depending on the ambient temperature. During this time the
internal temperature stabilized chamber is warming up to the default set point of 37
degrees.
You still can use the device and access the functionality of the Voltage Divider by going
to the “Setup” menu and selecting “Non-Align”. This will allow going through the
various configurations and perform functional measurements. However the 7520
specifications are not guaranteed until the temperature chamber is stabilized.
Once the warming up is complete the screen will indicate “Warmed up”.
At this point you will need to select “Self-Align” found under the “Setup” menu. If you
attempt to run this “Self-Align” before the system is warmed up it will not be initiated
since this function cannot be done until the unit has reached a stable temperature. The
user will be brought to the “Self-Alignment” screen where the user will see the
“Warming up” progress bar. After warming up is completed, the Self-Alignment will
start automatically. Progress of the Self-Alignment function is shown for each stage of
the divider by a progress bar and a “Self-Alignment in process” appears in the status bar
of all screens. After successful completion of the “Self-Alignment” the bottom banner of
the screens displays” Self-Alignment passed”. The Self Alignment takes about 2 hours to
complete.
WARNING: If the 7520 has been used in the “Non Align” mode with a voltage higher
than 25 V, the “Self Alignment” should not be invoked for 6 hours in order to ensure
temperature stability.
If the warm-up fails, the status will show “Warm up failed”. Also note that if this
message is displayed any time after continuous use it could be the result of either the
7520 being in an environment that is too warm or the temperature control has failed. Be
aware that the proximity of another piece of equipment could cause warm air to blow on
the Voltage Divider and cause the triggering of the “Warm up Failed” alarm.
If the warm-up fails, power down the 7520 for an hour and ensure the environment is
within the operating limits, and then power it back on. If the temperature chamber still
fails to stabilize then the unit must be returned to the factory for repair.
If the Self-Alignment fails, the status bar will display “Self-Alignment failed”. If this
happens it is recommended to initiate the Self-Alignment function a second time by
pressing “Self-Align” in the “Setup” screen. If the problem persists the unit needs to be
return to the factory.

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3. MANUAL OPERATION
3.1. FRONT PANEL
.
Figure 3-1: Front Panel Guildline Model 7520
1. TOUCH SCREEN INTERFACE - Used for front panel operation. Refer to section
3.3 for operation.
2. VOLTAGE INPUT - Terminals for connection to the input of the voltage divider
resistance chain.
3. NULL DETECTOR - Terminals for connection to an external null detector.
4. VOLTAGE REFERENCE - Terminals for connection of a reference voltage
standard.
5. VOLTAGE OUTPUT - Terminals for connection to the outputs of the voltage
divider chain.
6. GUARD - Terminal for connection of the internal passive guard of the voltage
divider chain.
7. GND - Terminal for connection to the internal ground tied to the power line ground
(i.e. earth).
2
4
6
1
3
5
7

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3.2. REAR PANEL
Figure 3-2: Rear Panel Guildline Model 7520
1. BOOTLOADER SWITCH - Switch to allow firmware upgrade.
2. IEEE-488 - Access for IEEE-488 interface bus for external control.
3. USB INTERFACE BUS - Type B connector used to connect voltage divider to
external controller (i.e. computer).
4. CHASSIS - Terminal for connection to the chassis tied to power line ground (i.e.
earth).
5. POWER - Line input voltage on/off switch.
6. FUSE - 1/2 A Time Delay for 100 V –127 V, 1/4 A Time Delay for 220 V –240 V.
7. 100 V –240 V AC POWER INPUT - IEC Line cord to AC mains. 100 V to 240 V
± 10 %; 45 Hz to 66 Hz.
1
3
5
7
2
4
6

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3.3. FRONT PANEL OPERATION
The Precision Voltage Divider is operated manually using the touch screen interface.
The GUI (Graphical User Interface) navigates through all of the functions and operation
of the 7520. The navigation is straightforward and is described in the following diagram
of the screen/menu hierarchy.
Figure 3-3: Guildline Model 7520 Menu/Screen Hierarchy
Note: The display responds better with the use of touch screen stylus rather than a
finger.
WARNING: NEVER CHANGE OR ENGAGE A VOTAGE DIVIDER MODE OF
OPERATION WHILE LIVE VOLTAGE IS PRESENT. DOING SO CAN
DAMAGE THE VOLTAGE DIVIDER, OTHER CONNECTED EQUIPMENT
AND POSSIBLY RESULT IN INJURY OR DEATH. THE VOLTAGE DIVIDE
CAN BE OPERATED UP TO 1100V AND THEREFORE LEATHAL VOLTAGES
MAY BE PRESENT ON INPUT TERMINALS OR EVEN OUTPUT TERMINALS
IF USED INCORRECTLY.
Main
Password
Status
Comparator
Open
10mV
100mV
1V
10V
100V
1000V
Divider
Open
1000:1
100:1
10:1
1:1
10V
+REF
Log
Setup
Calibration
Parameters
Self-Align
Non-Align
System
Parameters

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3.4. TOUCH SCREEN DISPLAY FUNCTIONS
3.4.1. Opening Banner/Main Display Screen
The opening banner appears on start-up of the 7520. The opening banner
provides system information of the 7520 such as firmware revision, and system
date/time of the 7520. The opening banner is also the root of the menu system.
There are 5 main menu areas on the 7520 indicated by “Divider”, “Comparator”,
“Setup”, “Status”, and “Log”. Touch either of these grey areas to activate the
corresponding menu features. The Status Bar located at the bottom of the screen
indicates the status information for the Voltage Divider and is present in all
screens of the user interface.
Note: The first two selections are for the two different operational modes of
the 7520. These two modes are the “Divider” mode of operation and the
“Comparator” mode of operation.
The “Divider” selection corresponds to a straightforward voltage divider where
the voltage provided on the “Voltage Input” terminals is simply divided by the
chosen ratio and this divided voltage is provided on the “Voltage Output”
terminals.
The “Comparator” selection corresponds to a comparison voltage divider where
the voltage provided on the “Voltage Input” terminals is compared to a reference
voltage connected to the “Reference Voltage” terminals. This is accomplished
with an external null detector through the “Null Detector” terminals.