Fluke 1537-II User manual

April 2017 Rev. 3, 9/23 (English)
© 2017-2023 Fluke Corporation. All rights reserved.
Specications are subject to change without notice.
All Product names are trademarks of their respective companies.
1535/1537/1537-II
Insulation Tester
Users Manual

LIMITED WARRANTY AND LIMITATION OF LIABILITY
The Fluke 1537 will be free from defects in material and workmanship for 3 years from the date
of purchase.
The Fluke 1535 will be free from defects in material and workmanship for 1 year from the date
of purchase.
The Fluke 1537-II will be free from defects in material and workmanship for 5 years from the
date of purchase.
This warranty does not cover fuses, disposable batteries, or damage from accident, neglect,
misuse, alteration, contamination, or abnormal conditions of operation or handling. Resellers
are not authorized to extend any other warranty on Fluke’s behalf. To obtain service during the
warranty period, contact your nearest Fluke authorized service center to obtain return authorization
information, then send the product to that Service Center with a description of the problem.
THIS WARRANTY IS YOUR ONLY REMEDY. NO OTHER WARRANTIES, SUCH AS FITNESS
FOR A PARTICULAR PURPOSE, ARE EXPRESSED OR IMPLIED. FLUKE IS NOT LIABLE
FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES,
ARISING FROM ANY CAUSE OR THEORY. Since some states or countries do not allow the
exclusion or limitation of an implied warranty or of incidental or consequential damages, this
limitation of liability may not apply to you.
China Service Center
Fluke Corporation Rm 101, 1/F, Tong Heng Tower
P.O. Box 9090 No. 4 Hua Yuan Road,
Everett, WA 98206 Hai Dian District, Beijing
U.S.A. 100088, P.R.C.
Hotline: [phone]
11/99

i
Table of Contents
Introduction ....................................................................................................1
Contact Fluke.................................................................................................2
Safety Information..........................................................................................2
Unpack the Tester ..........................................................................................2
The Tester ......................................................................................................3
Pushbuttons............................................................................................3
Tester On/O󰀨........................................................................................... 5
Display ....................................................................................................6
Guard Terminal Use ................................................................................7
Insulation Test Settings ..................................................................................9
Preset Test Voltage Selection ................................................................. 9
Program a Test Voltage (1537/1537-II only) ...........................................9
Select a Ramp or Steady-State Test (1537/1537-II only)......................10
Set a Timed Test (1537/1537-II only).................................................... 10
Polarization Index (PI)........................................................................... 11
Dielectric Discharge (1537/1537-II only)...............................................12
Dielectric Absorption Ratio....................................................................13
Test Circuit Connections .............................................................................. 14
Before an Insulation Test..............................................................................15
Insulation Test ..............................................................................................16
Store Test Results (1537/1537-II only)..................................................19
View Test Results Stored in Memory (1537/1537-II only) .....................19
Delete Test Results Stored in Memory (1537/1537-II only) .................. 21
V ac / V dc / Resistance (1537/1537-II only)................................................22
1537/1537-II PC Software............................................................................24
Maintenance.................................................................................................25
Cleaning................................................................................................25
Battery Replacement ............................................................................ 25
Product Disposal...................................................................................26
Parts and Accessories..................................................................................26
General Specications .................................................................................28
Electrical Specications ...............................................................................28
Principle of Measurement and Resistance...................................................32

1
Introduction
The Fluke 1535/1537/1537-II Insulation Testers (the Tester or Product) are high-
voltage insulation testers to validate general circuits, such as switchgear, motors,
and cables.
The Tester features:
• Large liquid crystal display (LCD)
• Preset test voltages: 250 V, 500 V, 1000 V, 2500 V
• Insulation measurement: 200 kΩ to 500 GΩ
• Polarization Index (PI) measurement
• Dielectric Absorption Ratio (DAR) measurement
• Auto power o󰀨 after 10 minutes of inactivity
The 1537/1537-II also includes:
• V ac/V dc/Resistance measurement
• Programmable test voltages: 250 V to 2500 V in 100 V steps
• Dielectric Discharge (DD) measurement
• Ramp mode that linearly increases (100 V/s) the applied test voltage
• Test timer and storage for test results with user-dened ID tag
• Breakdown voltage indication
• Mini USB serial port for download of test data
• PC software

2
1535/1537/1537-II
Users Manual
Contact Fluke
Fluke Corporation operates worldwide. For local contact information, go to our
website: www.uke.com.
To register your product, or to view, print, or download the latest manual or manual
supplement, go to our website.
To contact Fluke, call Technical Support China at [phone].
[phone] uke-info@uke.com
Safety Information
Make sure to read the Safety Information booklet that shipped with your Product.
Unpack the Tester
The Tester includes these items:
• Insulation Tester (includes batteries)
• Quick Reference Guide
• Safety Information
• Test Cables with Alligator Clips (red, black, green)
• Soft Carrying Case
• Test Report
The 1537/1537-II also includes a USB Cable.
See Table 8 for a list of parts. If the Tester is damaged or an item is missing,
contact the place of purchase.
Not all models are available in all regions.

3
Insulation Tester
The Tester
The Tester
Table 1 shows the location of the Tester features.
Table 1. Features
30V MAX
2
3
1
4

Item Description
1LCD
2USB Port (1537/1537-II only)
3Input Terminals
4Pushbuttons

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1535/1537/1537-II
Users Manual
Pushbuttons
Table 2 shows the location of each pushbutton and describes the functions.
Table 2. Pushbuttons

1234
6
5
7
10
9
8
Item Description
Model
1535 1537/
1537-II
1Power On / Power O󰀨 ● ●
2
DAR / PI / DAR + PI Selection ●
DAR / PI / DAR + PI / DD / Ramp Selection ●
3Test Start/Stop: Push and hold for 1 s to start a
test. Push again to stop a test. ● ●
4
Voltage Setting: 250 V / 500 V / 1000 V / 2500 V ● ●
Resistance Setting: value comparison ●
5Backlight On/O󰀨 ● ●
6Test Time Set/Cancel ●
7Record/Enter ●
8
scrolls through the test results stored in
memory for all records.
scrolls through available test parameters
for selected function.
●
9Delete Data ●
10 V ac / V dc / Resistance Selection ●

5
Insulation Tester
The Tester
Also use to access these menu items:
• Voltage adjustment in 100 V for each step
• Time limit xx-xx
• T - 0 to 99 minutes
T1, T2, T3 - T1 < T2 < T3
T1 > 0 seconds, T3 <1000 seconds
• Show test parameters
• Change the name of the ID tag for the test result
• Push to make the selection.
Tester On/O󰀨
Push to turn on the Tester.
The Tester does a self-check, shows the software version, and starts in the
Insulation Resistance Idle mode.
In Insulation Resistance Idle mode:
• Change test parameters
• Start an insulation test
• View stored test results (1537/1537-II only)
• Download test results (1537/1537-II only)
WCaution
If the object under test is highly capacitive, it can take a long time
for the Product to discharge. Do not turn o󰀨 the Product or remove
test leads until the discharge is complete.
When on, push >1 second to turn o󰀨 the Tester.

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1535/1537/1537-II
Users Manual
Display
Table 3 shows the location of each display feature.
XW Warning
To prevent possible electrical shock, re, or personal injury:
• Before and after any tests, do a voltage test to conrm that the
Tester does not detect the presence of hazardous voltage.
• If the Tester beeps continuously before the insulation test starts
and there is hazardous voltage, disconnect test leads and remove
power from the circuit under test.
Table 3. Display Features
2
3
4
5
6 7 9 10 11 12
13
14
15
16
17
18
8
1
19
20
Item Description
1Ramp mode
2Dielectric Discharge
3Polarization Index
4Dielectric Absorption Ratio
5Electrical breakdown in Ramp mode
6Interference present; readings could be out of specied accuracy range
7Continuity (1537/1537-II only)
8Test Voltage Setting
9Insulation test voltage
10 Discharging

7
Insulation Tester
The Tester
Table 3. Display Features (cont.)
Item Description
11 Possible hazardous voltage is at the test terminals (L to E and V to COM)
12 Battery Status
13 Delete/Delete All
14 Save
15 Bar graph display of insulation resistance
16 V ac or V dc voltage indicator
17 Insulation and resistance measurement indicator
18 Text display; shows voltage, test current, capacitance, programmable
test voltages, and menu options
19 Memory Status
20 Pass/Fail
Guard Terminal Use
Note
Insulation resistance is measured between the Earth terminal (E) and
Live terminal (L) output connections. The Guard terminal (G) is at the
same potential as the E terminal but is not in the measurement path.
For most tests, use only two test leads. Connect the E and L test leads to the
corresponding inputs on the Tester. Connect the test lead probes to the circuit
under test. The Guard (G) terminal is left unconnected.
For the best accuracy when you measure very high resistances, use three-wire
measurements including G. G is at the same potential as E, and can be used to
prevent surface leakage or other unwanted leakage currents from degrading the
accuracy of the insulation resistance measurement.

8
1535/1537/1537-II
Users Manual
Figure 1 shows how to measure the resistance from one of the conductors to the outer
shield. In this case, there is a leakage current along the surface of the inner insulation
near the end of the cable. This leakage adds to the current that the negative terminal
senses, and causes the Tester to read a lower resistance than it should.
Figure 1. Surface Leakage Current
L
E
Shield
Surface Leakage
Current
Figure 2 shows how to prevent surface current leakage with a lead connected from
the Guard terminal to a conductor that surrounds the inner insulation. The surface
leakage current is directed to the Guard terminal. This removes the leakage current
from the measurement path between the positive and negative terminals, and
improves the accuracy of the test readings.
Figure 2. Guard Terminal Connection
E
G
L
Shield
Leakage Current
Optional

9
Insulation Tester
Insulation Test Settings
Figure 3
shows how make the measurement setup better. Connect the Guard
terminal to the unused wire and attach it to the inner insulation. This ensures that
the Tester measures the leakage between the selected conductor and the outer
shield, but removes the leakage path between conductors.
Figure 3. Improved Guard Terminal Connection
E
G
L
Shield
Leakage Current
Insulation Test Settings
Preset Test Voltage Selection
To make a preset test voltage selection:
1. Turn on the Tester.
2. Push to scroll through the preset test voltage options (250 V, 500 V, 1000 V,
2500 V).
The test voltage selection shows on the display.
Note
The actual test voltage can be up to 10 % higher than the selected
test voltage.
Program a Test Voltage (1537/1537-II only)
To set a test voltage in between the preset test voltages, proceed as follows:
1. Turn on the Tester.
2. Push to select the test voltage.
3. Continue to push to scroll through the preset test voltage options (250 V,
500 V, 1000 V, 2500 V). Select the voltage closest to the level required.
The test voltage selection shows on the display.
4. Push or to increase and decrease the voltage in 100 V steps until the
correct voltage level shows.

10
1535/1537/1537-II
Users Manual
Note
The test voltage can be up to 10 % higher than the test voltage
you select.
Select a Ramp or Steady-State Test (1537/1537-II only)
The ramp test function is an automated test that checks insulation for a breakdown.
During a ramp test, the output voltage starts at 0 V and increases linearly (100 V/s)
until it reaches the specied test voltage or until the Tester senses a sudden drop in
measured resistance.
If the Tester senses a sudden drop in resistance:
• Ramp stops
• Tester automatically discharges
If the test successfully meets compliance without breakdown, the result is the same
as a normal insulation test and shows the data.
To enable or disable the ramp function:
1. With the Tester turned on, push to go to the Ramp test function. When the
ramp test is on, RAMP shows on the display.
Set a Timed Test (1537/1537-II only)
You can control the duration of an insulation test by setting a timer. The time (test
duration) can be set in 1-minute increments up to 99 minutes.
At the end of the elapsed time, the insulation test is complete and the test stops.
To set a test time limit:
1. With the Tester turned on, push to enter the Timed Test Menu.
2. Push or to congure the time.
3. Push to set the time limit.

11
Insulation Tester
Insulation Test Settings
Polarization Index (PI)
As part of the insulation test, the Tester measures and stores polarization index
(PI), when appropriate. A polarization index test requires 10 minutes to complete.
Therefore, the Tester will start a countdown at 10 minutes. When an insulation test
reaches 10 minutes, the polarization test is complete. The results are available for
display during a test or when you store the test results and view the record PI eld.
See Figure 4 .
The eld is identied by:
min1
min10
R
R
PI =
Figure 4. Polarization Index (PI)
1 2
2x = PI
10 min.
min1
min10
R
R
PI =

12
1535/1537/1537-II
Users Manual
Dielectric Discharge (1537/1537-II only)
The dielectric discharge (DD) test, also known as the re-absorption current test, is a
measurement of the current during dielectric discharge of the equipment being tested.
The measurement principle is as follows:
1. Equipment to be tested is rst charged for 30 minutes to reach a stable state
(capacitance charging and polarization are completed and the only current
owing is the leakage current).
2. Equipment is then discharged through a resistor inside the megaohmmeter and
the current that ows is measured. This current is made up of the capacitance
charging current and the re-absorption current that combines to give the total
dielectric discharge current. This current is measured after a standard time of
1 minute. The current depends on the overall capacitance and the nal test
voltage. See Figure 5.
The value DD is calculated with this formula:
CV
I
DD
×
=
I = current after 1-minute discharge
V = voltage before discharge
C = measured object capacitor
Figure 5. Dielectric Discharge
12
4x = DD
Discharge
1 min.
V x C
I
DD =
I
V
C
= current after 1-min. discharge
= voltage before discharge
= measured object capacitor

13
Insulation Tester
Insulation Test Settings
Dielectric Absorption Ratio
If appropriate, as part of the insulation test, the Tester stores the dielectric
absorption ratio (DAR) with the measurement. A DAR test has a 1-minute duration
and is measured and stored as invalid data for all insulation tests <1 minute. The
DAR test automatically stops when the insulation test time reaches 1 minute. The
results are available for display after test or by storing the test results and viewing
the DAR eld in record. See Figure 6 .
The eld is identied by:
s
R
R
DAR
30
min1

s
R
R
DAR
15
min1

[CN]
The Tester also does the DAR test in accordance with the Chinese standards:
s
R
R
DAR
30
min1

s
R
R
DAR
15
min1

[CN]
Note
If appropriate, as part of the insulation test, the Tester stores the
capacitance measurement. The results are available for display after the
test is complete by viewing the capacitance eld in the stored record.
Figure 6. Dialectric Absorption Ratio
1 min.
1
1x = DAR
30 sec
1 min
R
R
DAR =
2

14
1535/1537/1537-II
Users Manual
Test Circuit Connections
XW Warning
To prevent possible electric shock or personal injury:
• Disconnect power and discharge all high-voltage capacitors before
you measure resistance.
• Connect the Earth (E) test lead before the live (L) test lead and
remove the L test lead before the E test lead.
• Before and after tests, do a voltage test to conrm that the Tester
does not detect the presence of hazardous voltage. See
Table 3 . If
a hazardous voltage is shown on the display, remove power from
the circuit under test and disconnect test leads.
To connect to the circuit under test:
1. Put the test leads into the correct terminals. See
Table 4 .
2. Connect the test leads to the circuit under test.
Table 4. Test Lead Connections
30V MAX
E
L
2
1
Item Description
1E - Earth Terminal
2L - Live Terminal

15
Insulation Tester
Before an Insulation Test
Note
The Tester does not have specied accuracy below 200 kΩ . When you
do a test below 200 kΩ or with the leads shorted, the Tester can show a
reading. This is normal for the input circuitry conguration for this Tester.
Only the readings within the specied accuracy range are accurate.
Before an Insulation Test
The Tester includes features that let you adapt the test to your requirements.
You can:
• Dene a test voltage
• Measure polarization index (PI)
• Measure dielectric absorption ratio (DAR)
1537/1537-II only:
• Make a ramp test selection
• Measure dielectric discharge (DD)
• Compare insulation resistance
• Set a time limit/duration for the test
Use these features alone or in combination. Congure or validate (as appropriate)
each feature before you start an insulation test. For connections, see Figure 7 .
Figure 7. Insulation Test Connections
30V MAX
L
E

16
1535/1537/1537-II
Users Manual
Insulation Test
XW Warning
To prevent possible electrical shock or personal injury:
• Be aware that measuring insulation resistance requires the
application of potentially dangerous voltages to the circuit. This
may include exposed bonded metalwork.
• Remove all power from the circuit under test and discharge circuit
capacitance before testing a circuit with the Tester.
• Before a test starts, ensure that the installation is wired correctly
and no personnel are endangered by any tests.
• Connect the test leads to the Tester inputs before you make any
connections to the circuit under test.
PI/DAR is valid in these conditions:
• Capacitance is ≤0.1 μF or Resistance is ≤100 MΩ.
• Resistance is ≥200 kΩ and Capacitance ≤2 μF.
• Current is ≥50 nA.
To do an insulation test:
1. With the Tester turned on, set the available measurement options to meet your
test requirements. These include:
• Test Voltage – Set range: 250 V to 2500 V (1537/1537-II only: 100 V steps)
• Ramp Test – (optional, 1537/1537-II only)
• Time Limit – (optional, 1537/1537-II only)
2. Connect the probes to the circuit under test, see
Figure 7 .

17
Insulation Tester
Insulation Test
XW Warning
To prevent possible electric shock or personal injury:
• Before and after tests, do a voltage test to conrm that the Tester does
not detect the presence of hazardous voltage. See
Table 3 .
• If the Tester beeps continuously before the insulation test starts and
there is hazardous voltage, disconnect test leads and remove power
from the circuit under test.
3. Push to select 250 V, 500 V, 1000 V, or 2500 V.
4. Push for 1 second to start the insulation test.
The Tester makes three beeps as the test begins, and X ashes on the display
to indicate potentially hazardous voltages may be present on the test terminals.
The display shows the insulation resistance after the circuit stabilizes. The bar
graph shows this value continuously (in real time) as a trend. See
Table 5 .
Table 5. Insulation Resistance Measurements
2
1
Item Description
1Digital main display
2Bar graph