3.3Slew Rate Measurement and Actual Transition time14
3.4Constant Voltage (CV) Mode14
3.4.1Congure CV Parameters14
3.5Constant Power (CW) Mode14
3.5.1Congure CW Parameters14
3.6Constant Resistance (CR) Mode15
3.6.1Congure CR Parameters15
4Front Panel Operation16
4.1Local Mode/Remote Mode16
4.2Constant Current (CC) Mode16
4.2.1Congure CC Parameters16
4.3Slew Rate Measurement and Actual Transition time17
4.4Constant Voltage (CV) Mode17
4.4.1Congure CV Parameters17
4.5Constant Power (CW) Mode17
4.5.1Congure CW Parameters17
4.6Constant Resistance (CR) Mode18
4.6.1Congure CR Parameters18
4.7CR-LED Test Function18
4.7.1Setup18
4.7.2External Triggering19
2
5Rear Panel Functions20
5.1Remote Sensing20
5.2External Triggering21
5.3Current Monitoring (I Monitor)21
5.3.1Remote Sensing21
5.3.2Current Monitoring (I Monitor)21
6Advanced Functions22
6.1Short Operation22
6.2Short-circuit Analog Function22
6.3Transient Operation22
6.3.1CC Mode23
6.3.2CV, CW, and CR modes23
6.4LIST Operation23
6.4.1Congure List24
6.4.2Run List24
6.4.3Disable List Mode25
6.5Battery Test Function25
6.5.1Test Conguration25
6.5.2Enable Battery Test Mode26
6.5.3Recall Battery File26
6.5.4Start Battery Test26
6.6Program Mode26
6.6.1Example: Small AC/DC power supply test26
6.6.2Start Auto Test File31
6.6.3Recall Test File31
6.7Measurement of Voltage Rise Time31
6.7.1Set initial Voltage and Final Voltage31
6.8Ripple Function32
7Conguration Functions33
7.1VON Function33
7.2Menu Operation33
7.3System Menu33
7.4Menu Options33
7.5System Menu (System)34
7.6Cong Menu35
8System Settings36
8.1Run Recall Edit36
8.2To recall the settings36
8.3To run the OPP test36
8.4Key Lock36
8.5Restore Factory Default Settings37
8.5.1Congure Power-On State37
8.5.2Load On Knob38
8.5.3Congure Trigger Source38
8.5.4Save/Recall Instrument Settings38
8.5.5Select Storage Group39
8.5.6Save Settings39
8.5.7Recall Settings39
8.5.8Display Input On Timer40
8.5.9Remote Interface Setup40
8.5.10RS-23240
8.5.11CONFIG Menu41
8.5.11.1Von Operation41
3
8.5.12Congure Protection Settings41
8.5.13PROTECT MENU41
8.5.14Max-P A-Limit P-Limit Time41
8.5.15Overcurrent Protection (OCP)42
8.5.16Overpower Protection (OPP)43
8.5.17Recall OPP File44
8.5.18Overvoltage Protection (OVP)45
8.5.19Over-temperature Protection (OTP)45
8.5.20Reverse Voltage Protection (LRV/RRV)45
8.5.21Congure Timed Input45
8.5.22Measurement Congurations46
9Protection Functions47
9.1OCP Test Function47
9.2OPP Test Function48
9.3OPP TEST48
9.4Over Voltage Protection (OVP)48
9.5Over Current Protection (OCP)49
9.6Over Power Protection (OPP)49
9.7Over Temperature Protection (OTP)49
9.8Reverse Voltage Protection (LRV)50
10 Remote Operation51
10.1Interface Connection51
10.2Serial Interface51
10.2.1GPIB51
10.2.2USBTMC51
10.2.3Remote Commands51
11 Troubleshooting Guide52
11.1General52
11.2Remote Control52
11.3Error Information References52
11.4Exception handling52
12 Specications54
13 Service Information55
14 LIMITED THREE-YEAR WARRANTY56
4
General Information
1.1 Product Overview
The 8500B Series DC Electronic Loads are versatile instruments used for static and dynamic testing of DC power supplies,
batteries, DC-to-DC converters, battery chargers, and other applications including fuel-cell, and solar cell test. Primary
modes include constant voltage (CV), constant current (CC), constant resistance (CR), and constant power (CW). A
wide range of dynamic loading applications can also be simulated through user-programmable slew rates, load levels,
duration, and conducting voltage. Further, transient, list mode, battery mode, and LED modes further extend testing
capabilities. Versatile triggering options allow the dynamic load behavior to be synchronized with other events. The DC
load is remotely programmable via the TTL serial interface. This interface requires 0-5V signal levels and can connect
to typical serial ports via an adapter such as the IT-E132B.
Features:
• CC/CV/CR/CW operating modes
• List mode
• Transient mode
• Measurement speed up to 40 kHz
• Remote sense function
• Battery test function
• OCP and OPP automatic test
• CR-LED function
• Store/recall up to 100 setups
• Analog current monitoring
• Adjustable slew rate in CC mode
• OVP/OCP/OPP/OTP and reverse voltage protection
1.2 Package Contents
Please inspect the instrument mechanically and electrically upon receiving it. Unpack all items from the shipping carton,
and check for any obvious signs of physical damage that may have occurred during transportation. Report any damage
to the shipping agent immediately. Save the original packing carton for possible future reshipment. Every instrument is
shipped with the following contents:
• 8500B series DC Electronic load
• IT-E132B USB to TTL adapter
• AC Power Cord
• Certicate of Calibration
• Test Report
5
Verify that all items above are included. If anything is missing, please contact B&K Precision.
1.3 Product Dimensions
All models are designed to t in a standard 19-inch rackmount. The dimensions are shown in Figure 1.1.
Figure 1.1 External Dimensions - Half-rack models
1.4 Rackmount Installation
The instrument can be installed in a standard 19 inch rack. For half-rack models, the optional rackmount kit IT-E151 is
required. Figure 1.2 shows one of the half-rack sized units using the IT-E151 rackmount kit. This rackmount kit also
accomodates up to two half-rack models installed side by side. The full size 8514B includes rack mounting ears.
Figure 1.2 Half-Rack sized Unit
1.5 Front Panel Overview
See Figure 1.3.
6
Item Description
1VFD Display
2Power Switch
3Numeric Input and Advanced Functions
4Mode keys and Input Control
5Navigation Keys
6Input Terminals
7Rotary Input Knob
Figure 1.3 Front Panel
1.5.1 Combination Keys
Pressbutton rst and then other keys to activate the more advanced functions.
+Turn short circuit on or o.
+Start or stop transient condition.
+Set LIST operation parameters.
+Store the DC Load state in non-volatile memory.
+Turn on or o battery testing function.
+Enter auto test function.
+Display product’s Model/SN/Version.
7
+System menu setting
+Congure menu setting
+Press this button if you need a pause when running an auto test le.
+Cause an immediate trigger.
+Enter OCP test function.
+Set detailed parameters in CC/CV/CW/CRmode.
+Enter OPP test function.
+Recall the DC Load state from non-volatile memory.
+Key lock function
1.6 Rear Panel Overview
The rear panel connections are shown in Figure 1.4.
Item Description
1Power Input and Fuse Holder
2AC Voltage Switch
3Current Monitor Output
4Remote Sense and Trigger Input
5TTL (5V) Communication DE-9 Connector
Figure 1.4 Rear Panel
8
1.7 Display Overview
Item Description
1Measured Voltage
2Measured Current
3Measured Power
4Set Value
5Input O indicator, lit when input is o
6Operation mode indicators (CC, CV, CW, CR)
12Remote control active indicator
13Error indicator
14Waiting for Trigger indicator
15Timer indicator
16External indicator
16Remote Sense active indicator
17Protection event indicator
18Auto range
19Key Lock indicator
20Shift indicator
9
Getting Started
Before connecting and powering up the instrument, please review and go through the instructions in this chapter.
2.1 Input Power
The load has a selectable AC input that accepts line voltage input within:
VoltageFrequency
115 V (+/-10%) or 230 V (+/- 10%) 47 Hz – 63 Hz
Table 2.1 Input Power Requirements
Use the line voltage selector switch in the back to switch between 110 V and 220 V operation.
Disconnect all cables including the power cord from the instrument when changing the instrument’s line
voltage. After changing the line voltage setting, ensure the instrument has fuses of the proper ratings and types for
the selected line voltage before applying line power.
2.2 Fuse Requirements
An AC input fuse is necessary when powering the instrument. Below is a table of the fuse required for all models operating
with either 110 VAC or 220 VAC input. See Table 2.2. The fuses are 5mm x 20mm High Energy Slow Blow type
(ceramic casing with sand ll).
Model Fuse Specication (110 VAC) Fuse Specication (220 VAC)
8542B 1.25 A, 250 V500 mA, 250 V
8500B 1.25 A, 250 V500 mA, 250 V
8502B 1.25 A, 250 V500 mA, 250 V
8510B 2.5 A, 250 V1.25 A, 250 V
8514B 2.5 A, 250 V1.25 A, 250 V
Table 2.2 Fuse Ratings
2.2.1 Fuse Replacement
Follow the steps below to replace to check the fuse:
1. Locate the fuse box next to the AC input connector in the rear panel, see Figure 2.1.
2. With a small at blade screwdriver, insert into the fuse box slit to pull and slide out the fuse box as indicated below.
3. Check and replace fuse (if necessary) for the desired line voltage operation.
2.3 Input Connections
The main DC input terminal is a screw type binding post terminal located in the front panel, holes are included for
inserting wires, and the binding post also includes “banana jack” connections. Each connection allows for dierent
10
Figure 2.1 Fuse Holder
current levels. The “banana” input is capable of up to 10 A of current. Any more current is not recommended and could
lead to excessive connector heating, melting and worse.
Note: The screws on the terminals can be completely removed to allow for ring type adapters. The screw posts are
7mm in diameter.
Due to the high current rating of the DC load, proper wire sizes are necessary for safe connectivity and to prevent wires
from overheating.
Before connecting wires to the input terminals, turn OFF the load to avoid damage to the instrument and
the device under test (DUT).
High Current ConnectionLow (<10 A) Current Connection
Figure 2.2 Input Connections
2.4 Preliminary Check
Complete the steps in this section to verify that the load is ready for use.
2.4.1 Verify AC Input Voltage
Verify and check to make sure proper AC voltages are available to power the instrument. The AC voltage range must
meet the acceptable specication as explained in Section ??.
Connect AC power cord to the AC receptacle in the rear panel and press the power switch to the ON position to turn
ON the instrument. It will run through a self test procedure with the screen shown below:
11
2.4.2 Self-test Errors
Connect AC power cord to the AC receptacle in the rear panel and press the power switch to the ON position to turn
ON the instrument. Various elements of the system are checked during the power-on self test routine. If any occur, they
are reported during the power-up procedure. See Section 11 for troubleshooting and error information details. During
self-test, the display displays “System Init”, and dots are displayed showing the test progress level.
2.4.3 Input Check
Follow the steps below to check that the load is operating correctly, and that the load elements (power transistors) are
not damaged. A DC power supply rated for at least 5V and 1 A is required for this check.
1. Connect the input terminal to a DC power supply and congure the supply to output 5 V and current limit to 1 A.
2. Power on the load. The display will show the “OFF” annunciator above the voltage display.
3. Turn on the DC power supply’s output. Observe the load’s measured voltage display, it should read approximately 5
V.
4. Press the “CC” button to enable the constant current load mode.
5. Use the keypad to enter 0.5 A. Press the Enter key to set the value.
6. The display should show CC = 0.500A on the bottom right.
7. Press “On/O” to enable the load. The “On/O” button should light up, and the “O” indicator on screen should
disappear. The measured current should now display a value close to 0.5 A.
8. This setup veries that the load is drawing power correctly from the power supply.
If the load does not show 5 V, or shows signicant current draw from the connected power supply, the load may be
damaged and need service. If when the supply is connected, showing 5 V on the load’s display, and no current is drawn,
the load may be damaged and need service.
Note: If the load is not drawing power from the DC power supply, check all load protection limits and settings within
the menu to verify that the load is congured to allow drawing power at 5V, 0.500 A. Also, verify that the CC mode
parameters are setup to operate within the congured valid ranges by pressing+
If after checking all of the above, and verifying the power supply used for testing is not at fault, contact B&K for further
assistance.
2.4.4 Check Model and Firmware Version
The model and rmware version can be veried by using the *IDN? query remote command. It can also be found from
the front panel:
1. Pressand
2. The display will show the following:
3. This shows the model to be a BK8542B with Firmware: 1.45
4. Press (esc) to return to the normal display.
12
Front Panel Operation
The electronic load provides the following modes:
• Constant current (CC) operation mode
• Constant voltage (CV) operation mode
• Constant resistance (CR) operation mode
• Constant power (CW) operation mode
3.1 Local Mode/Remote Mode
The 8500B series can either be operated locally or remotely. When in “Remote” mode, the RMT indicator will be lit.
When in this mode, the front panel of the load is disabled and all commands are issued via the serial interface. In order
to exit “Remote” mode and work in “Local” mode, press the “Local” button. This is the small grey button on the left
hand side of the numeric keypad.
3.2 Constant Current (CC) Mode
In this mode, the load will draw the specied current as long as the source is capable of delivering it. The load uses
transistors in parallel to implement the load circuit, and as such there are some limits. For example, the load has a nite
minimum resistance determined by the RdsOn of the transistors. Next, given the resistance limits, there is a limit to the
amount of current that may be drawn for a given voltage. The datasheet shows curves for this limit in the section called
“Low Voltage Operation”. Please refer to the datasheet for details for each model.
3.2.1 Congure CC Parameters
There are several parameters that should be setup prior to operating in CC mode. First, enable the “CC” mode of
operation by pressing the CC mode key. Next, enter the setup menu by pressing “Shift” and then the “CV” key. Above
the “CV” key, “Setup” is written. The following are the available menu items, scroll through them with the up/down
arrow keys or by entering a value and pressing enter.
Range This denes the maximum allowed current set value. Use this limit to protect against acciden-
tally entering excessive current values either from the keypad or dial.
High This is the voltage high limit for the automatic test mode, it does not apply otherwise. During
automatic test mode, the device under test (DUT) must be operating below the congured value
for the test to PASS upon completion. If the DUT operates above the congured value, the test
will FAIL upon completion.
Low This parameter refers to the voltage low limit for the automatic test mode. During automatic
test mode, the DUT must be operating above the congured value for the test to PASS upon
completion. If the DUT operates below the congured value, the test will FAIL upon completion.
Rise Up/ Fall Down These parameters dene the current slew rate of the load as it changes to a new programmed
value. The programmed slew rate takes eect immediately when set, so if the transient or triggered modes are active, it will apply immediately.
13
3.3 Slew Rate Measurement and Actual Transition time
Current slew rate is dened as the change in current over time. A programmable slew rate allows a controlled transition
from one load setting to another. The actual transition time is dened as the time for the input to change from 10% to
90%, or 90% to 10% of the programmed current values. The graph below illustrates slew rate measurements.
Between the 10% and 90% region, the slew rate can be measured by observing the steepest slope portion. In case of very
large load changes, e.g. from no load to full load, the actual transition time will be larger than the expected (measured)
time. For this reason, the rmware allows the user to program slew rate values outside of the specied slew rate ranges.
The minimum transition time for all programmable slew rates is also limited in cases where the transition from one setting
to another is very small, due to bandwidth limitations of the load.
3.4 Constant Voltage (CV) Mode
In this mode, the electronic load will attempt to sink enough current to control the source voltage to the programmed
value.
3.4.1 Congure CV Parameters
There are several parameters that should be set up prior to operating in CV mode. Press so that it lights up, then press
) and to access Setup for CV mode. The setup menu will be shown:
Range This value will also act as a limit to how much voltage the load can be congured.
High This is the current upper limit for the automatic test mode. The system must be operating be-
low the congured value for the test to PASS upon completion. If the DUT operates above this
value, the test will FAIL.
Low This is the current lower limit for the automatic test mode. The system must be operating be-
low the congured value for the test to PASS upon completion. If the DUT operates below this
value, the test will FAIL.
3.5 Constant Power (CW) Mode
In this mode, the electronic load will consume a constant power. When input voltage increases, the input current will
decrease, while power (P = V*I) will remain the same. This is a sampled system, so the performance is not as fast as in
CC and CV modes.
3.5.1 Congure CW Parameters
There are several parameters that should be set up prior to operating in CW mode. Press
so that it lights up, then press )and to access “Setup” for CW mode. The setup menu will be shown:
The setup parameters are: Range, High (Voltage limit), and Low (Voltage limit). Use the
) keys to select each parameter, and use the numeric keypad to change the value. Pressto conrm the change.
Range This value will also act as a limit the allowed power setting value.
High This parameter sets the upper voltage limit for the automatic test mode. If the voltage exceeds
this upper limit during the test, the test will fail.
High This parameter sets the lower voltage limit for the automatic test mode. If the voltage exceeds
this lower limit during the test, the test will fail.
14
3.6 Constant Resistance (CR) Mode
In this mode, the electronic load approximates a resistor. The current draw is varied by the load according to the input
voltage. The performance of this mode is not as fast as in CC or CV mode. This is because it is a sampled system and
response to changing input takes a nite amount of time.
3.6.1 Congure CR Parameters
There are several parameters that should be set up prior to operating in CR mode. Press
so that it lights up, then press )and to access Setup for CR mode. The setup menu will be shown:
The setup parameters are: Range, High (Voltage limit), and Low (Voltage limit). Use the (arrow keys) key to select each
parameter, and use the numeric keypad to change the value. Press (enter) to conrm the change.
Range This value will also act as a limit the allowed resistance setting value.
High This parameter sets the upper voltage limit for the automatic test mode. If the voltage exceeds
this upper limit during the test, the test will fail.
High This parameter sets the lower voltage limit for the automatic test mode. If the voltage exceeds
this lower limit during the test, the test will fail.
15
Front Panel Operation
The electronic load provides the following modes:
• Constant current (CC) operation mode
• Constant voltage (CV) operation mode
• Constant resistance (CR) operation mode
• Constant power (CW) operation mode
4.1 Local Mode/Remote Mode
The 8500B series can either be operated locally or remotely. When in “Remote” mode, the RMT indicator will be lit.
When in this mode, the front panel of the load is disabled and all commands are issued via the serial interface. In order
to exit “Remote” mode and work in “Local” mode, press the “Local” button. This is the small grey button on the left
hand side of the numeric keypad.
4.2 Constant Current (CC) Mode
In this mode, the load will draw the specied current as long as the source is capable of delivering it. The load uses
transistors in parallel to implement the load circuit, and as such there are some limits. For example, the load has a nite
minimum resistance determined by the RdsOn of the transistors. Next, given the resistance limits, there is a limit to the
amount of current that may be drawn for a given voltage. The datasheet shows curves for this limit in the section called
“Low Voltage Operation”. Please refer to the datasheet for details for each model.
4.2.1 Congure CC Parameters
There are several parameters that should be setup prior to operating in CC mode. First, enable the “CC” mode of
operation by pressing the CC mode key. Next, enter the setup menu by pressing “Shift” and then the “CV” key. Above
the “CV” key, “Setup” is written. The following are the available menu items, scroll through them with the up/down
arrow keys or by entering a value and pressing enter.
Range This denes the maximum allowed current set value. Use this limit to protect against acciden-
tally entering excessive current values either from the keypad or dial.
High This is the voltage high limit for the automatic test mode, it does not apply otherwise. During
automatic test mode, the device under test (DUT) must be operating below the congured value
for the test to PASS upon completion. If the DUT operates above the congured value, the test
will FAIL upon completion.
Low This parameter refers to the voltage low limit for the automatic test mode. During automatic
test mode, the DUT must be operating above the congured value for the test to PASS upon
completion. If the DUT operates below the congured value, the test will FAIL upon completion.
Rise Up/ Fall Down These parameters dene the current slew rate of the load as it changes to a new programmed
value. The programmed slew rate takes eect immediately when set, so if the transient or triggered modes are active, it will apply immediately.
16
4.3 Slew Rate Measurement and Actual Transition time
Current slew rate is dened as the change in current over time. A programmable slew rate allows a controlled transition
from one load setting to another. The actual transition time is dened as the time for the input to change from 10% to
90%, or 90% to 10% of the programmed current values. The graph below illustrates slew rate measurements.
Between the 10% and 90% region, the slew rate can be measured by observing the steepest slope portion. In case of very
large load changes, e.g. from no load to full load, the actual transition time will be larger than the expected (measured)
time. For this reason, the rmware allows the user to program slew rate values outside of the specied slew rate ranges.
The minimum transition time for all programmable slew rates is also limited in cases where the transition from one setting
to another is very small, due to bandwidth limitations of the load.
4.4 Constant Voltage (CV) Mode
In this mode, the electronic load will attempt to sink enough current to control the source voltage to the programmed
value.
4.4.1 Congure CV Parameters
There are several parameters that should be set up prior to operating in CV mode. Press so that it lights up, then press
) and to access Setup for CV mode. The setup menu will be shown:
Range This value will also act as a limit to how much voltage the load can be congured.
High This is the current upper limit for the automatic test mode. The system must be operating be-
low the congured value for the test to PASS upon completion. If the DUT operates above this
value, the test will FAIL.
Low This is the current lower limit for the automatic test mode. The system must be operating be-
low the congured value for the test to PASS upon completion. If the DUT operates below this
value, the test will FAIL.
4.5 Constant Power (CW) Mode
In this mode, the electronic load will consume a constant power. When input voltage increases, the input current will
decrease, while power (P = V*I) will remain the same. This is a sampled system, so the performance is not as fast as in
CC and CV modes.
4.5.1 Congure CW Parameters
There are several parameters that should be set up prior to operating in CW mode. Press
so that it lights up, then press )and to access “Setup” for CW mode. The setup menu will be shown:
The setup parameters are: Range, High (Voltage limit), and Low (Voltage limit). Use the
) keys to select each parameter, and use the numeric keypad to change the value. Pressto conrm the change.
Range This value will also act as a limit the allowed power setting value.
High This parameter sets the upper voltage limit for the automatic test mode. If the voltage exceeds
this upper limit during the test, the test will fail.
High This parameter sets the lower voltage limit for the automatic test mode. If the voltage exceeds
this lower limit during the test, the test will fail.
17
4.6 Constant Resistance (CR) Mode
In this mode, the electronic load approximates a resistor. The current draw is varied by the load according to the input
voltage. The performance of this mode is not as fast as in CC or CV mode. This is because it is a sampled system and
response to changing input takes a nite amount of time.
4.6.1 Congure CR Parameters
There are several parameters that should be set up prior to operating in CR mode. Press
so that it lights up, then press )and to access Setup for CR mode. The setup menu will be shown:
The setup parameters are: Range, High (Voltage limit), and Low (Voltage limit). Use the (arrow keys) key to select each
parameter, and use the numeric keypad to change the value. Press (enter) to conrm the change.
Range This value will also act as a limit the allowed resistance setting value.
High This parameter sets the upper voltage limit for the automatic test mode. If the voltage exceeds
this upper limit during the test, the test will fail.
High This parameter sets the lower voltage limit for the automatic test mode. If the voltage exceeds
this lower limit during the test, the test will fail.
4.7 CR-LED Test Function
The Constant Resistance LED mode roughly simulates a diode characteristic. There are 2 main parameters that are set
to accomplish this, the overall resistance and diode threshold voltage (Vd). At input voltages above the threshold (Vd),
the resistance of the load decreases. For example, set the Vd to 1.6 V, R to 0.1 and connect a current limited power
supply. Set the power supply voltage limit to 5 V, and the current limit to 300 mA. When the input is enabled, the
voltage at the input will be approximately 1.6 V, and the current will be 300 mA. This is equivalent to a resistance of 16
Ohms, much larger than the set value of 0.1 Ohms. See Table 4.1.
Like in CR mode, a resistance value is also set. This value sets the slope of the diode characteristic. A 3 V VD, 0.1
Ohms, and 1.38 A results in 3𝑉 + 0.1Ω ∗ 1.38𝐴 = 3.18𝑉.
Voltage CurrentEquivalent Load Resistance
1.000innite
1.5815mA105 Ohms
1.620.215 A7.5 Ohms
1.630.35.4 Ohms
1.691 A (limit changed) 1.7 Ohms
Table 4.1 CR Mode example
4.7.1 Setup
Enable CR-LED mode via+. Use the arrow keys to move the ashing value “ON”. Pressto conrm
and move on. The next screen shows the VD value. Enter the desired threshold voltage and press. CR LED mode
is now setup.
Note: As in CR mode, the control system speed can make loading switching power supplies problematic.
18
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