APS 42L Series User manual

Operation Manual
42L Series – Rev 1.2 P/N 160906-10
42LSeries
ProgrammableDCLoad
ADAPTIVE Power Systems
Worldwide Supplier of Power Equipment
TM
Copyright 2014, Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.

CONTENTS
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 2 of 88
PAGE LEFT INTENTIONALLY LEFT BLANK FOR HARDCOPY VERSIONS OF THIS DOCUMENT

CONTENTS
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 3 of 88
Table of Contents
1Contact Information ...................................................................................................................8
2Front Matter...............................................................................................................................9
2.1 Limited Warranty .................................................................................................................................... 9
2.2 Service and Spare Parts Limited Warranty ............................................................................................ 9
2.3 Safety Information................................................................................................................................... 9
2.4 Safety Notices ........................................................................................................................................ 11
3Product Overview.....................................................................................................................13
3.1 General Description............................................................................................................................... 13
3.2 Operating Modes .................................................................................................................................. 13
3.2.1 Constant Current Mode ................................................................................................................................... 14
3.2.2 Constant Resistance Mode .............................................................................................................................. 14
3.2.3 Constant Voltage Mode ................................................................................................................................... 14
3.2.4 Constant Power Mode ..................................................................................................................................... 15
3.3 Static versus Dynamic Operating Modes ............................................................................................. 15
3.3.1 Programmable Parameters.............................................................................................................................. 16
3.3.2 Slew Rates ......................................................................................................................................................... 16
3.3.3 Determining Actual Transition Times .............................................................................................................. 17
3.4 Current Read-back................................................................................................................................. 19
3.5 Analog Input Mode ............................................................................................................................... 19
3.6 Product Features ................................................................................................................................... 19
3.7 Accessories Included ............................................................................................................................. 20
3.7.1 Accessory Installation ....................................................................................................................................... 21
3.8 Interface Options................................................................................................................................... 22
4Technical Specifications............................................................................................................23
4.1 Operating Ranges .................................................................................................................................. 23
4.2 Operating Modes .................................................................................................................................. 23
4.3 Protection Modes.................................................................................................................................. 23
4.4 Dynamic Operation Mode .................................................................................................................... 24
4.5 Metering ................................................................................................................................................ 24
4.6 Miscellaneous ........................................................................................................................................ 24
4.7 AC Input & Cooling ................................................................................................................................ 24
4.8 Dimensions & Weight ........................................................................................................................... 25
4.9 Environmental ....................................................................................................................................... 25
4.10 Voltage versus Current Operating Envelope Charts............................................................................ 26
4.10.1 Model 42L0860 V-I Curves ............................................................................................................................... 27
4.10.2 Model 42L0824 V-I Curves ............................................................................................................................... 28
4.10.3 Model 42L0803 V-I Curves ............................................................................................................................... 29
5Unpacking and Installation .......................................................................................................30
5.1 Inspection .............................................................................................................................................. 30
5.2 Load Module Installation and Removal in Mainframe........................................................................ 30
5.2.1 Module Removal .............................................................................................................................................. 30
5.2.2 Module Installation .......................................................................................................................................... 31
5.3 Cleaning.................................................................................................................................................. 32
5.4 Powering Up .......................................................................................................................................... 32
5.5 In Case of Malfunction .......................................................................................................................... 32
5.6 Load Connections.................................................................................................................................. 33

CONTENTS
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 4 of 88
5.7 Analog Programming Input................................................................................................................... 34
5.8 Load Current Slew Rate......................................................................................................................... 34
6Front Panel Operation ..............................................................................................................36
6.1 Front Panel Layout ................................................................................................................................ 36
6.2 User Controls and Readouts ................................................................................................................. 37
6.3 Operating Flowchart for 42L Series Load Modules ............................................................................. 59
6.4 Go/NoGo LIMIT Testing ........................................................................................................................ 60
6.4.1 Limits ................................................................................................................................................................. 60
6.4.2 Go/NoGo Testing in CC Mode.......................................................................................................................... 60
6.4.3 Go/NoGo Testing in CC Dynamic Mode .......................................................................................................... 61
6.4.4 Go/NoGo Testing in CR Mode.......................................................................................................................... 61
6.4.5 Go/NoGo Testing in CV Mode ......................................................................................................................... 62
6.4.6 Go/NoGo Testing in CP Mode.......................................................................................................................... 62
6.5 Initial Power-on Settings ....................................................................................................................... 63
6.5.1 Model 42L0860 Power-on Settings ................................................................................................................. 63
6.5.2 Model 42L0824 Initial Settings......................................................................................................................... 64
6.5.3 Model 42L0803 Initial Settings......................................................................................................................... 64
7Load Connections, Applications and Protection Features.........................................................65
7.1 INPUT Terminals .................................................................................................................................... 65
7.1.1 Banana Jack Connectors................................................................................................................................... 65
7.1.2 Y-hook / Spade Lug Terminals.......................................................................................................................... 65
7.1.3 Lead Wire Insertion .......................................................................................................................................... 65
7.1.4 Banana Jack Connector and Spade Lug Terminals.......................................................................................... 66
7.1.5 Plug Connector and Lead Wire Insertion ........................................................................................................ 66
7.2 Wire Size ................................................................................................................................................ 66
7.2.1 Wire Size Guidelines ......................................................................................................................................... 67
7.3 Connecting a UUT.................................................................................................................................. 68
7.4 Polarity and Ground – Multiple Output Power Supplies..................................................................... 69
7.5 Voltage Sense Input Terminals ............................................................................................................. 70
7.6 Parallel Operation.................................................................................................................................. 71
7.6.1 Parallel Mode Connection................................................................................................................................ 71
7.6.2 Allowable Operating Modes ............................................................................................................................ 71
7.6.3 Exceptions ......................................................................................................................................................... 71
7.7 Series Operation .................................................................................................................................... 71
7.8 Zero-Voltage Loading ............................................................................................................................ 72
7.9 Protection Features............................................................................................................................... 73
7.9.1 Over Voltage Protection................................................................................................................................... 73
7.9.2 Over Current Protection................................................................................................................................... 73
7.9.3 Over Power Protection..................................................................................................................................... 73
7.9.4 Over Temperature Protection ......................................................................................................................... 74
7.9.5 Reverse Polarity Protection Indication ............................................................................................................ 74
8Auto Sequence Programming Examples ...................................................................................75
8.1 Overview................................................................................................................................................ 75
8.2 Edit Mode .............................................................................................................................................. 75
8.3 Test Mode.............................................................................................................................................. 76
8.4 AUTO TEST SEQUENCE Example .......................................................................................................... 77
9Short Circuit, OPP and OCP Test Examples ...............................................................................79
9.1 Overview................................................................................................................................................ 79
9.2 SHORT Test ............................................................................................................................................ 79

CONTENTS
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 5 of 88
9.3 OPP Test................................................................................................................................................. 80
9.4 OCP Test................................................................................................................................................. 81
10 Remote Control Programming..................................................................................................82
10.1 Overview................................................................................................................................................ 82
11 Calibration ................................................................................................................................83
11.1 Overview................................................................................................................................................ 83
11.2 Calibration Interval................................................................................................................................ 83
11.3 Calibration Coefficients ......................................................................................................................... 83
11.4 Calibration Procedures.......................................................................................................................... 83
12 CE MARK Declaration of Conformity.........................................................................................84
13 RoHS Material Content Declaration..........................................................................................85
Index ...............................................................................................................................................86

CONTENTS
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 6 of 88
Table of Tables
Table 3-1: Dynamic Current Mode Parameters....................................................................................................16
Table 3-2: Included Accessories ...........................................................................................................................20
Table 6-1: Front Panel Display and Keyboard Functions ......................................................................................58
Table 6-3: Model 42L0860 – CH A - Power-on Settings........................................................................................63
Table 6-3: Model 42L0860 – CH B - Power-on Settings........................................................................................63
Table 6-4: Model 42L0824 – CH A & CH B - Power-on Settings............................................................................64
Table 6-5: Model 42L0803 Power-on Settings .....................................................................................................64
Table 7-1: Load Wire Size Table............................................................................................................................67
Table 7-2: Multiple Output DC Supply Polarity Connection .................................................................................69
Table 9-1: Auto-Test Sequence Example Values ..................................................................................................77

CONTENTS
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 7 of 88
Table of Figures
Figure 3-1: Dynamic Current Wave Form .............................................................................................................15
Figure 3-2: Rise Time Performance Limits ............................................................................................................17
Figure 3-3: 42L Series Accessories ........................................................................................................................20
Figure 3-4: Load and sense connections using Y-hooks/spade lugs .....................................................................21
Figure 3-5: Load and sense connections using banana plugs - insertion .............................................................21
Figure 3-6: Load and sense connections using banana plugs - inserted ..............................................................22
Figure 5-3: Load Module Removal........................................................................................................................31
Figure 5-4: Location and Pin-out of Analog Programming Input Connector ........................................................34
Figure 5-7: Effect of Current Slew Rate Settings on Power Supply Testing..........................................................35
Figure 6-1: 44M04 Chassis with 41L0630 Series Loads Front Panel View ............................................................36
Figure 6-2: Front Panel User Controls and Indicators ..........................................................................................37
Figure 6-3: Operation Flow Chart - 42L Series Load Module................................................................................59
Figure 6-4: LIMIT Test in CC Mode........................................................................................................................60
Figure 6-5: LIMIT Test in Dynamic CC Mode.........................................................................................................61
Figure 6-6: LIMIT Test in CR Mode .......................................................................................................................61
Figure 6-7: LIMIT Test in CV Mode .......................................................................................................................62
Figure 6-8: LIMIT Test in CP Mode........................................................................................................................62
Figure 7-1: Doubling wire size using spade lugs ...................................................................................................66
Figure 7-2: DC Load Connection with Internal Voltage Sense..............................................................................70
Figure 7-3: DC Load Connection with External Voltage Sense .............................................................................70
Figure 7-7: Parallel Load Connection....................................................................................................................71
Figure 7-8: Zero Volt Load Connection .................................................................................................................72
Figure 9-1: Auto-Test Sequence Example Illustration ..........................................................................................77

SECTION 1: CONTACT INFORMATION
1Contact Information
AMERICA/CANADA
Adaptive Power Systems
Irvine, USA
Phone: [phone]
Fax: [phone]
Email: suppo[email protected]om
EUROPE
Caltest Instruments Ltd.
Guildford, United Kingdom
Phone: [phone]
Fax: [phone]
Email: suppo[email protected]om
CHINA
PPST Shanghai Co. Ltd.
Shanghai, China
Phone: [phone]
Fax: [phone]
Email: suppo[email protected]om
Web: http://www.adaptivepower.com

SECTION 2: FRONT MATTER
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 9 of 88
2Front Matter
2.1 Limited Warranty
Adaptive Power Systems, Inc. (APS) warrants each unit to be free from defects in material
and workmanship. For the period of one (1) year from the date of shipment to the
purchaser, APS will either repair or replace, at its sole discretion, any unit returned to the
APS factory in Irvine, California or one of its designated service facilities. It does not cover
damage arising from misuse of the unit or attempted field modifications or repairs. This
warranty specifically excludes damage to other equipment connected to this unit.
Upon notice from the purchaser within (30) days of shipment of units found to be defective
in material or workmanship, APS will pay all shipping charges for the repair or replacement.
If notice is received more than thirty (30) days from shipment, all shipping charges shall be
paid by the purchaser. Units returned on debit memos will not be accepted and will be
returned without repair.
This warranty is exclusive of all other warranties, expressed or implied.
2.2 Service and Spare Parts Limited Warranty
APS warrants repair work to be free from defects in material and workmanship for the
period of ninety (90) days from the invoice date. This Service and Spare Parts Limited
Warranty applies to replacement parts or to subassemblies only. All shipping and packaging
charges are the sole responsibility of the buyer. APS will not accept debit memos for
returned power sources or for subassemblies. Debit memos will cause return of power
sources or assemblies without repair.
This warranty is exclusive of all other warranties, expressed or implied.
2.3 Safety Information
This chapter contains important information you should read BEFORE attempting to install
and power-up APS Equipment. The information in this chapter is provided for use by
experienced operators. Experienced operators understand the necessity of becoming
familiar with, and then observing, life-critical safety and installation issues. Topics in this
chapter include:
•Safety Notices
•Warnings
•Cautions
•Preparation for Installation
•Installation Instructions
Make sure to familiarize yourself with the SAFETY SYMBOLS shown on the next page. These
symbols are used throughout this manual and relate to important safety information and
issues affecting the end user or operator.

SECTION 2: FRONT MATTER
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 10 of 88
SAFETY SYMBOLS
Direct current (DC)
Alternating current (AC)
Both direct and alternating current
Three-phase alternating current
Off (Supply)
On (Supply)
Protective Earth (ground) terminal
Caution: Refer to this manual before this Product.
Caution, risk of electric shock
Fuse

SECTION 2: FRONT MATTER
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 11 of 88
2.4 Safety Notices
SAFETY SUMMARY
The following general safety precautions must be observed during all phases of operation,
service, and repair of this instrument. Failure to comply with these precautions or with
specific warnings elsewhere in this manual violates safety standards of design, manufacture,
and intended use of the instrument. Adaptive Power Systems assumes no liability for the
customer's failure to comply with these requirements.
GENERAL
This product is a Safety Class 1 instrument (provided with a protective earth terminal). The
protective features of this product may be impaired if it is used in a manner not specified in
the operation instructions.
ENVIRONMENTAL CONDITIONS
This instrument is intended for indoor use in an installation category I, pollution degree 2
environments. It is designed to operate at a maximum relative humidity of 80% and at
altitudes of up to 2000 meters. Refer to the specifications tables for the ac mains voltage
requirements and ambient operating temperature range.
BEFORE APPLYING POWER
Verify that the product is set to match the available line voltage and the correct fuse is
installed.
GROUND THE INSTRUMENT
This product is a Safety Class 1 instrument (provided with a protective earth terminal). To
minimize shock hazard, the instrument chassis and cabinet must be connected to an
electrical ground. The instrument must be connected to the AC power supply mains through
a properly rated three-conductor power cable, with the third wire firmly connected to an
electrical ground (safety ground) at the power outlet. Any interruption of the protective
(grounding) conductor or disconnection of the protective earth terminal will cause a
potential shock hazard that could result in personal injury.
FUSES
Only fuses with the required rated current, voltage, and specified type (normal blow, time
delay, etc.) should be used. Do not use repaired Fuses or short circuit the fuse holder. To do
so could cause a shock or fire hazard.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.
Do not operate the instrument in the presence of flammable gases or fumes.

SECTION 2: FRONT MATTER
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 12 of 88
KEEP AWAY FROM LIVE CIRCUITS.
Operating personnel must not remove instrument covers. Component replacement and
internal adjustments must be made by qualified service personnel. Do not replace
components with power cable connected. Under certain conditions, dangerous voltages
may exist even with the power cable removed. To avoid injuries, always disconnect power,
discharge circuits and remove external voltage sources before touching components.
DO NOT SERVICE OR ADJUST ALONE.
Do not attempt internal service or adjustment unless another person, capable of rendering
first aid and resuscitation, is present.
DO NOT EXCEED INPUT RATINGS.
This instrument may be equipped with a line filter to reduce electromagnetic interference
and must be connected to a properly grounded receptacle to minimize electric shock
hazard. Operation at line voltages or frequencies in excess of those stated on the data plate
may cause leakage currents in excess of 5.0 mA peak.
DO NOT EXCEED LOAD INPUT VOLTAGE RATING.
WARNING
DO NOT EXCEED LOAD INPUT VOLTAGE RATING
This instrument does NOT have a means to disconnect its Load input from a
connected power supply. If the voltage applied to the Load input exceeds its
maximum rating – even if the load is turned completely off – damage to the load
WILL occur. Damage caused by exceeded maximum load input voltage under any
circumstance is NOT covered by the manufacturer’s product warranty. Remove any
load input connections when the load is not in use, even when it is turned off.
DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.
Because of the danger of introducing additional hazards, do not install substitute parts or
perform any unauthorized modification to the instrument. Return the instrument to an
Adaptive Power Systems Sales and Service Office for service and repair to ensure that safety
features are maintained.
Instruments that appear damaged or defective should be made inoperative and secured
against unintended operation until they can be repaired by qualified service personnel.

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 13 of 88
3Product Overview
This chapter provides an overview of the APS 42L Series modular programmable DC loads. It
introduces the reader to general operating characteristics of these loads.
3.1 General Description
The APS 42L Series modular electronic loads are designed to perform test, evaluation and
burn-in of DC power supplies and batteries. The 42L Series differs from the 41L Series in
that each module has two input channels (dual channel) whereas the 41L Series is
comprised of a series of more conventional, single channel load modules. Thus, in addition
to addressing a 42L Series module with a channel reference, a CHA or CHB selection is
required to address one or the other channel. In all other respects, they are functionally
similar to 41L series modules.
The 42L Series of electronic load modules are operated from within a suitable mainframe.
The 44M01, 44M02 and 44M04 mainframes allow 1, 2 or 4 modules (2, 4 or 8 load channels)
to be operated at the same time. The mainframes provide the necessary mains power
conversion along with computer and analogue interfaces. Front panel memory store and
recall functions are provided. A total of 150 memory locations are available to store the set-
up of the load modules within a mainframe. It is also possible to program and recall a test
sequence consisting of different steps against time. Please refer to the separate 44M01,
44M02 and 44M04 operating manuals for the mainframe functions.
Mainframe model 44M01: P/N 160901-10
Mainframe model 44M02: P/N 160902-10
Mainframe model 44M04: P/N 160904-10
The APS 42L Series can be operated from the front panel (manual mode) or using RS232,
USB, LAN (Ethernet) or GPIB remote control.
The VI curve constant power contours of the various 42L Series modules are shown in the
Technical Specification Section. All models have dual range capability for enhanced accuracy
and resolution at lower power levels. Maximum current and power capability depends on
the specific module type.
3.2 Operating Modes
Available operating modes for all models are:
•Constant Current (CC) mode
•Constant Resistance (CR) mode
•Constant Voltage (CV) mode
•Constant Power (CP) mode.
A more detailed explanation of each mode and under what condition each mode is most
appropriate to use follows.

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 14 of 88
3.2.1 Constant Current Mode
This is the most commonly used mode of operating
when testing a voltage source such as a DC power
supply, battery, AC/DC converter or ADC. In this
mode of operation, the load will sink a constant level
of current as set by the user, regardless of any voltage
variations. A real time feedback loop ensures a stable
current under any voltage variation of the DC supply
or battery.
This mode is recommended for load regulation
testing, loop stability testing, battery discharge testing
and any other form of voltage regulation loop testing.
3.2.2 Constant Resistance Mode
In Constant Resistance mode, the load will sink
current directly proportional to the sensed DC input
voltage. The ratio between DC voltage and current is
linear per ohms law and can be set by the user within
the operating range of the DC load. The current is
defined by the formula shown here where R is the set
value in CR mode and V is the dc input voltage from
the unit under test.
=/
CR mode is useful for battery discharge testing of battery systems used to power constant
impedance loads as the voltage will decrease as the battery discharges over time resulting in
reduced current sinking.
3.2.3 Constant Voltage Mode
In Constant Voltage mode, the load will attempt to
sink as much current as needed to reach the
programmed voltage setting. This mode should only
be used with current controlled DC power sources.
Note: Most DC power supplies are voltage controlled,
i.e. they regulate the output voltage to a predefined
voltage level. Such DC voltage supplies should not be
tested using CV mode as the DC supply voltage
regulation loop will conflict with the DC load control
loop.
VOLTAGE
CURRENT
V
I
CURRENT I
VOLTAGE
V
VOLTAGE
CURRENT
V
I

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 15 of 88
3.2.4 Constant Power Mode
In Constant Power mode, the DC load will attempt to
maintain the programmed Power dissipation by sinking
more or less current at the voltage sensed. The current is
defined by the formula shown below.
=/
Constant power mode is useful for battery discharge
testing as it simulates constant power drain on the
battery, regardless of battery charge state.
3.3 Static versus Dynamic Operating Modes
The 42L Series supports both STATIC and DYNAMIC CC mode. Static mode uses a constant
load level whereas dynamic mode allows rapid changes between two pre-set current sink
levels using programmable current slew rates and duty cycle.
Static Constant Current mode presents a static load condition as the load current remains
constant. This tests load regulation of a DC power supply under steady state operating
conditions.
To test voltage regulation under dynamic load conditions, specific changes in current level
and current slew rates must be applied to the DC supply under test. The dynamic CC mode is
provided for this application.
The 42L Series offer a wide range of dynamic load conditions with independent rise and fall
current slew rate programming in Constant Current mode.
Figure 3-1: Dynamic Current Wave Form
VOLTAGE
CURRENT
V
I
LOAD CURRENT
TIME
I
t
T-rise T-fallT-HIGH T-LOW
SLEW
SLEW
HIGH LOAD LEVEL
LOW LOAD LEVEL

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 16 of 88
3.3.1 Programmable Parameters
There are six programmable parameters to generate dynamic wave form or pulse wave
form, the 42L Series loads will sink current from power source proportional to the dynamic
wave form, the dynamic wave form definition is shown in Figure 3-1. Available settings are:
Parameter
Description
Type
Current High
Highest programmed load current
Current Setting
Current Low
Lowest programmed load current
Current Setting
T-High
Duration at High current setting
Time (secs)
T-Low
Duration at Low current setting
Time (secs)
Rising Slew Rate
Current Slew Rate from Low to High Current
A/sec
Falling Slew Rate
Current Slew Rate from High to Low Current
A/sec
Table 3-1: Dynamic Current Mode Parameters
The resulting current waveform has the following characteristics:
Period = T-High + T-Low
Frequency = 1 / ( T-High + T-Low )
Duty Cycle = T-High / ( T-High + T-Low )
3.3.2 Slew Rates
Slew rate is defined as the change in current or voltage over time. A programmable slew
rate allows a controlled transition from one load setting to another to minimize induced
voltage drops on inductive power wiring, or to control induced transients on a test device
(such as would occur during power supply transient response testing).
In cases where the transition from one setting to another is large, the actual transition time
can be calculated by dividing the voltage or current transition by the slew rate. The actual
transition time is defined as the time required for the input to change from 10% to 90% or
from 90% to 10% of the programmed current excursion. In cases where the transition from
one setting to another is small, the small signal bandwidth of the load limits the minimum
transition time for all programmable slew rates. Because of this limitation, the actual
transition time is typically longer than the expected time based on the slew rate setting, as
shown in Figure 3-2.
Therefore, both minimum transition time and slew rate must be considered when
determining the actual transition time. See also section 5.13 “Load Current Slew Rate” on
page 34.

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 17 of 88
Figure 3-2: Rise Time Performance Limits
3.3.3 Determining Actual Transition Times
The minimum transition time (Tr min) for a given slew rate applies for smaller changes in
current as a percent of current range. At about a 30% or greater load change, the slew rate
starts to increase from the minimum transition time to the maximum transition time (Tr
max) at a 100% load change. The actual transition time will be either the minimum
transition time, or the total slew time (T-fall or T-rise) divided by the current slew rate,
whichever is longer.

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 18 of 88
Minimum Tr
Use the following formulas to calculate the minimum transition time for a given slew rate on
a 42L0860 module:
Maximum current range for this module is 60A so 30% of 60 = 18. The minimum required
slew rate can be calculated as follows:
 min = 
 (/)()  µs
Which is equivalent to:
 min = 
 (/)0.8 µs
For a programmed slew rate of 2.5A/s, this results in:
 min = 
.0.8 µs = 5.76 µs
Example 1:
Assume high current level (CCH) = 12A and low current level (CCL) = 0A. For a 42L0860, a
16A delta change in current represents less than 30% of full scale current this load module
(< 18A). If the programmed slew rate is set to 2.5A/s, the expected transition time would be:
 =. ()
.µs = 3.84 µs
However, we determined that Tr min for a slew rate of 2.5A/s is at least 5.76 µs so the
actual transition time will be limited to no less than 5.76 µs.
Maximum Tr
Use the following formula to calculate the maximum transition time for a given slew rate:
 max = (.)
 (/)0.8 µs
For a slew rate of 0.1A/s, this results in:
 max = 
.0.8 µs = 19.2 µs
Example 2:
Assume high current level (CCH) = 40A and low current level (CCL) = 0A. Since 40A
represents more than 30% of the current range for the module used (40 > 18). If the slew
rate is set to 0.1A/s, the expected transition time would be:
 =. ()
.µs = 12.8 µs
Since Tr max for a slew rate of 2.5A/s is 19.2 µs so the actual transition time will be lesser
of these two values or 12.8 µs.

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 19 of 88
3.4 Current Read-back
The load current levels and load status can be set from the front panel of each load module
or over the remote control interface. During testing, load input voltage and load current can
be read back but the current read back will typically display the average current level unless
the dynamic current frequency setting is low enough. An analog current monitor output is
provided to allow capturing of dynamic current on a digital storage scope or data recorder.
3.5 Analog Input Mode
A set of analog inputs is provided at the rear panel of the mainframe to allow analog
programming of load current using a function or arbitrary waveform generator. This allows
any current profile within the performance envelope of the DC load to be used for perform
dynamic load testing beyond the built in dynamic CC mode.
Note: This mode is supported in Constant Current (CC) and Constant Power (CP) modes
only.
3.6 Product Features
The following key characteristics apply to all 42L Series modules.
•Fully programmable electronic DC load with flexible configuration and dual range
capabilities.
•Dual load channels per module for testing multiple output DC supplies
•Full remote control of all load settings and metering read back.
•Dual high accuracy and high-resolution 5 digit voltage and current meters with
Go/NoGo determination.
•Built-in pulse generator includes wide Thigh/Tlow dynamic load range, independent
Rise/Fall load current slew rate control, and High/Low load level.
•Controllable load current slew rate of load level change,
•Load ON/OFF switch change and power supply turn ON.
•Short circuit test with current measure capability.
•Dedicated over current and over power protection test functions
•Automatic voltage sensing and external sense.
•Full protection from over power, over temperature, over voltage, and reverse
polarity.
•Variable fan speed control for quieter operation

SECTION 3: PRODUCT OVERVIEW
Entire Contents Copyright

2014 by Adaptive Power Systems, Inc. (APS) • All Rights Reserved • No reproduction without written authorization from APS.
42L Series Modular DC Load Operation Manual Page 20 of 88
3.7 Accessories Included
The following accessories are included with each 42L Series DC Load in the quantities shown
in the table below. If one or more of these items is missing upon incoming inspection of the
product, please contact Adaptive Power Systems customer service.
Item
Decsription
41L
42L
41D
42D
a
Banana plug, 4 mm, Red – Load connection
1
2
1
-
b
Banana plug, 4 mm, Black – Load connection
1
2
1
-
c
Banana plug, 2 mm, Red – VSENSE connection
1
2
3
8
d
Banana plug, 2 mm, Black – VSENSE connection
1
2
3
8
e
Y-hook Terminal, Large – Load connection
2
-
-
-
f
Y-hook Terminal, Small – V
SENSE
connection
2
4
4
4
g
BNC Cable, 3 feet – I Monitor
1
-
1
1
h
Operator Manual in Hardcopy format or PDF on CD ROM
1
1
1
1
i
Certificate of Conformance
1
1
1
1
Table 3-2: Included Accessories
Figure 3-3: 42L Series Accessories