Fluke 1535 User manual

1535/1537
Insulation Tester
Users Manual
April 2017 Rev. 1, 6/21 (English)
©2017-2021 Fluke Corporation. All rights reserved.
Specifications are subject to change without notice.
All Product names are trademarks of their respective companies.

LIMITED WARRANTY AND LIMITATION OF LIABILITY
The Fluke 1537 will be free from defects in material and workmanship for three years from
the date of purchase.
The Fluke 1535 will be free from defects in material and workmanship for one year 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.
11/99
Fluke Corporation
P.O. Box 9090
Everett, WA 98206-9090
U.S.A.
China Service Center
Rm 101, 1/F, Tong Heng Tower
No. 4 Hua Yuan Road,
Hai Dian District, Beijing
100088, P.R.C.
Hotline: [phone]

i
Table of C onten ts
Introduction......................................................................................................................... 1
Contact Fluke ..................................................................................................................... 2
Safety Information............................................................................................................ 2
Symbols................................................................................................................................ 5
Unpack the Tester ............................................................................................................ 6
The Tester............................................................................................................................ 7
Pushbuttons............................................................................................................... 7
Tester On/Off............................................................................................................. 9
Display.......................................................................................................................... 10
Guard Terminal Use................................................................................................. 11
Test Circuit Connections ............................................................................................... 13
Before an Insulation Test ............................................................................................... 14
Preset Test Voltage Selection ............................................................................ 15
Program a Test Voltage (1537 only) ................................................................. 15
Select a Ramp or Steady-State Test (1537 only)......................................... 16
Set a Timed Test (1537 only) ............................................................................... 16
Polarization Index (PI).............................................................................................. 17
Dielectric Discharge (1537 only)........................................................................ 17
Dielectric Absorption Ratio .................................................................................. 18
Insulation Test.................................................................................................................... 18
Store Test Results (1537 only)............................................................................ 20
View Test Results Stored in Memory (1537 only)........................................ 21
Delete Test Results Stored in Memory (1537 only) .................................... 23
V ac / V dc / Resistance (1537 only)........................................................................... 23
1537 PC Software............................................................................................................. 24
Maintenance ....................................................................................................................... 25
Cleaning....................................................................................................................... 25
Battery Replacement.............................................................................................. 25
Parts and Accessories........................................................................................... 26
General Specifications.................................................................................................... 28
Electrical Specifications................................................................................................. 28
Principle of Measurement and Resistance ............................................................. 32

1
Introduction
The Fluke 1535/1537 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)
•Presettestvoltages:250V, 500V, 1000V, 2500V
• Insulation measurement: 200kΩto 500GΩ
• Polarization Index (PI) measurement
• Dielectric Absorption Ratio (DAR) measurement
• Auto power off after 10minutes of inactivity
The 1537 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-defined ID tag
• Breakdown voltage indication
• Mini USB serial port for download of test data
•PCsoftware

1535/1537
Users Manual
2
Contact Fluke
Fluke Corporation operates worldwide. For local contact information, go to our
website: www.fluke.com.
To register your product, or to view, print, or download the latest manual or
manual supplement, go to our website.
[phone] [e-mail]
Safety Information
A Warning identifies hazardous conditions and procedures that are dangerous
to the user. A Caution identifies conditions and procedures that can cause
damage to the Product or the equipment under test.
XW Warning
To prevent possible electrical shock, fire, or personal injury:
Carefully read all instructions.
Read all safety information before you use the Product.
Do not alter the Product and use only as specified, or the
protection supplied by the Product can be compromised.
Do not use the Product around explosive gas, vapor, or in damp or
wet environments.
Do not use the Product if it is altered or damaged.
Disable the Product if it is damaged.
Do not use the Product if it operates incorrectly.
Use Product-approved measurement category (CAT), voltage, and
amperage rated accessories (probes, test leads, and adapters) for
all measurements.
Do not exceed the Measurement Category (CAT) rating of the
lowest-rated individual component of a Product, probe, or
accessory.
Fluke Corporation
P.O. Box 9090
Everett WA 98206-9090
U.S.A.
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands

Insulation Tester
Safety Information
3
Do not use in CAT III or CAT IV environments without the protective
cap installed on test probe. The protective cap decreases the
exposed probe metal to <4 mm. This decreases the possibility of
arc flash from short circuits.
Comply with local and national safety codes. Use personal
protective equipment (approved rubber gloves, face protection,
and flame-resistant clothes) to prevent shock and arc blast injury
where hazardous live conductors are exposed.
Examine the case before you use the Product. Look for cracks or
missing plastic. Carefully look at the insulation around the
terminals.
Do not use test leads if they are damaged. Examine the test leads
for damaged insulation and measure a known voltage.
Do not touch voltages >30 V ac rms, 42 V ac peak, or 60Vdc.
Do not apply more than the rated voltage, between the terminals or
between each terminal and earth ground.
Measure a known voltage first to make sure that the Product
operates correctly.
Limit operation to the specified measurement category, voltage, or
amperage ratings.
The battery door must be closed and locked before you operate
the Product.
Connect the common test lead before the live test lead and remove
the live test lead before the common test lead.
Remove all probes, test leads, and accessories before the battery
door is opened.
Remove all probes, test leads, and accessories that are not
necessary for the measurement.
Keep fingers behind the finger guards on the probes.
Replace the batteries when the low battery indicator shows to
prevent incorrect measurements.
Use the correct terminals, function, and range for measurements.
Place test leads in proper input terminals.
Do not work alone.

1535/1537
Users Manual
4
Do not use in distribution systems with voltages higher than 660 V.
Use only recommended test leads.
Remove all power from the circuit under test and discharge circuit
capacitance before testing resistance or capacitor with the tester.
Results of measurement can be adversely affected by the
impedances of additional operating circuits connected in parallel
or by transient currents.
Before and after testing, confirm that the Tester does not indicate
the presence of a hazardous voltage. If a hazardous voltage is
shown on the display, remove power from the circuit under test or
allow the installation capacitance to fully discharge.
Do not disconnect the test leads before a test has been completed
and the test voltage at the terminals has returned to zero. This
ensures that any charged capacitance is fully discharged.
Use the guard terminal only as specified in this manual. Do not
allow other foreign objects to come into contact with the guard
terminals as safety may be compromised.
Remove the input signals before you clean the Product.
Use only specified replacement parts.
Repair the Product before use if the battery leaks.
Be sure that the battery polarity is correct to prevent battery
leakage.
Do not operate the Product with covers removed or the case open.
Hazardous voltage exposure is possible.
Have an approved technician repair the Product.

Insulation Tester
Symbols
5
Symbols
Tab l e 1 lists the symbols used on the Tester and in the manual.
Tab l e 1 . S y mbo ls
Symbol Definition
XWARNING. HAZARDOUS VOLTAGE. Risk of electric shock.
WWARNING. RISK OF DANGER.
»Consult user documentation.
PConforms to European Union directives.
MBattery
RContinuity test or continuity beeper tone. (1537 only)
TDouble Insulated
6WARNING. Do not apply greater than 660 Volts.
Interference is present. Displayed value might be outside of
specified accuracy.
RAMP Ramp mode indicator
Electrical breakdown
DBoth direct and alternating current
JEarth
½
Measurement Category III is applicable to test and measuring
circuits connected to the distribution part of the building’s low-
voltage MAINS installation.
¾
Measurement Category IV is applicable to test and measuring
circuits connected at the source of the building’s low-voltage
MAINS installation.
~
This product complies with the WEEE Directive marking
requirements. The affixed label indicates that you must not
discard this electrical/electronic product in domestic
household waste. Product Category: With reference to the
equipment types in the WEEE Directive Annex I, this product is
classed as a category 9 “Monitoring and Control
Instrumentation” product. Do not dispose of this product as
unsorted municipal waste.

1535/1537
Users Manual
6
Unpack the Tester
The Tester includes these items:
• Insulation Tester (includes batteries)
• Quick Reference Guide
• Test Cables with Alligator Clips (red, black, green)
• Soft Carrying Case
•TestReport
The 1537 also includes a USB Cable.
See Tab l e 9 for a list of parts. If the Tester is damaged or an item is missing,
contact the place of purchase.

Insulation Tester
The Tester
7
The Tester
Tab l e 2 shows the location of the Tester features.
Pushbuttons
Tab l e 3 shows the location of each pushbutton and describes the functions.
Table 2. Features
Item Description
ALCD
BUSB Port (1537 only)
CInput Terminals
DPushbuttons
30V MAX
2
3
1
4


1535/1537
Users Manual
8
Table 3. Pushbuttons
Item Description
Model
1535 1537
APower On / Power Off 
BDAR / PI / DAR + PI Selection 
DAR / PI / DAR + PI / DD / Ramp Selection 
CTest Start/Stop: Push and hold for 1 s to start a
test. Push again to stop a test. 
DVoltage Setting: 250 V / 500 V / 1000 V / 2500 V 
Resistance Setting: value comparison 
EBacklight On/Off 
FTest Time Set/Cancel 
GRecord/Enter 
H
JK scrolls through the test results stored in
memory for all records.
LM scrolls through available test parameters
for selected function.

IDelete Data 
JV ac / V dc / Resistance Selection 

1234
6
5
7
10
9
8

Insulation Tester
The Tester
9
Also use L M 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
Ito make the selection.
Te s t e r O n /O f f
Push Ato 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 only)
• Download test results (1537 only)
WCaution
If the object under test is highly capacitive, it can take a long time
for the Product to discharge. Do not turn off the Product or remove
test leads until the discharge is complete.
When on, push A>1 second to turn off the Tester.

1535/1537
Users Manual
10
Display
Tab l e 4 shows the location of each display feature.
XW Warning
To prevent possible electrical shock, fire, or personal injury:
Before and after any tests, do a voltage test to confirm 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 4. Display Features
Item Description
ARamp mode
BDielectric Discharge
CPolarization Index
DDielectric Absorption Ratio
EElectrical breakdown in Ramp mode
FInterference present; readings could be out of specified accuracy
range
2
3
4
5
6 7 9 10 11 12
13
14
15
16
17
18
8
1
19
20

Insulation Tester
The Tester
11
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.
GContinuity (1537 only)
HTest Voltage Setting
ITe s t Vo l t a g e
JDischarging
KPossible hazardous voltage is at the test terminals
LBattery Status
MDelete/Delete All
NSave
OBar graph display of insulation resistance
PV ac or V dc voltage indicator
QInsulation and DMM resistance measurement indicator
RText display; shows voltage, test current, capacitance, programmable
test voltages, and menu options
SMemory Status
TPass/Fail
Table 4. Display Features (cont.)

1535/1537
Users Manual
12
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
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
Surface Leakage
Current
Shield
L
E
Leakage
Current
Shield
Optional
E
G
L

Insulation Tester
Test Circuit Connections
13
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
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 confirm that the Tester
does not detect the presence of hazardous voltage. See Table 4. 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 Ta bl e 5 .
2. Connect the test leads to the circuit under test.
Leakage
Current
Shield
E
G
L

1535/1537
Users Manual
14
Note
The Tester does not have specified accuracy below 200kΩ. When
you do a test below 200kΩor with the leads shorted, the Tester can
show a reading. This is normal for the input circuitry configuration for
this Tester. Only the readings within the specified accuracy range are
accurate.
Before an Insulation Test
The Tester includes features that let you adapt the test to your requirements.
Yo u c a n :
• Define a test voltage
• Measure polarization index (PI)
• Measure dielectric absorption ratio (DAR)
Table 5. Test Lead Connections
Item Description
AE - Earth Terminal
BL - Live Terminal
30VMAX
E
L
2
1


Insulation Tester
Before an Insulation Test
15
1537 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. Configure or validate (as
appropriate) each feature before you start an insulation test.
Preset Test Voltage Selection
To make a preset test voltage selection:
1. Turn on the Tester.
2. Push Eto 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 only)
To set a test voltage in between the preset test voltages, proceed as follows:
1. Turn on the Tester.
2. Push Eto select the test voltage.
3. Continue to push Eto 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.
Push Lor Mto increase and decrease the voltage in 100 V steps until the
correct voltage level shows.
Note
The test voltage can be up to 10 % higher than the test voltage you
select.

1535/1537
Users Manual
16
Select a Ramp or Steady-State Test (1537 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 specified test voltage or until the Tester
senses a sudden drop in measured resistance.
If the Tester senses a sudden drop in resistance:
•Rampstops
• 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 Cto go to the Ramp test function. When
the ramp test is on, RAMP shows on the display.
2. Push Dfor 1 second to start the test.
Set a Timed Test (1537 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 Gto enter the Timed Test Menu.
2. Push Lor Mto configure the time.
3. Push Ito set the time limit.
4. Push Dfor 1 second to start the test.

Insulation Tester
Before an Insulation Test
17
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 field. The field is identified by:
Dielectric Discharge (1537 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 first charged for 30 minutes to reach a stable
state (capacitance charging and polarization are completed and the only
current flowing is the leakage current).
2. Equipment is then discharged through a resistor inside the mega-
ohmmeter and the current that flows 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 final test voltage.
The value DD is calculated with this formula:
I= current after 1-minute discharge
V= voltage after 1-minute discharge
C= measured object capacitor
min1
min10
R
R
PI =
CV
I
DD × =