Array Electronic 3700 Series Programmable DC Electronic Load User Manual

Content

Overview

The 3700 Series Programmable DC Electronic Load is a single-input test instrument for evaluating DC power supplies, batteries, chargers, and other suitable power sources. It can draw a controlled electrical load in constant current, constant power, or constant resistance mode.

The series is intended for engineering laboratories, production testing, service work, and educational environments. A backlit LCD, numeric keypad, rotary control, programmable test sequences, and computer control support both quick manual checks and repeatable automated testing.

Specifications

Models: 3710A and 3711A
Inputs: One DC input
Input voltage range: 0 to 360 V DC
Maximum input current: 30 A
Maximum input power: 150 W for the 3710A; 300 W for the 3711A
Voltage accuracy: ±0.2% + 3 mV from 0.000 to 3.999 V; ±0.2% + 30 mV from 4.00 to 35.999 V; ±0.2% + 300 mV from 36.0 to 360.0 V
Current accuracy: ±0.2% + 3 mA from 0.000 to 2.999 A; ±0.2% + 30 mA from 3.00 to 30.00 A
Resolution: 1 mV for voltage and 1 mA for current
Minimum conductive resistance: Less than 0.08 Ω
Ripple: Less than 10 mVpp
Communication: RS-232, RS-485, and USB through the applicable interface arrangement
Program storage: Nine programs with up to 10 steps per program
AC supply: Switchable 110/220 V AC at 50/60 Hz
Weight: Approximately 5.0 kg
Dimensions: Approximately 212.6 mm wide, 88.1 mm high, and 250 mm deep

Detailed Description

The load absorbs power from the connected DC source and regulates the amount drawn according to the selected operating mode. The display shows measured current and voltage on the first line, while power, the active setting, and the operating mode appear on the second line.

The front panel includes a backlit LCD, numeric keypad, navigation keys, confirmation and escape keys, and a rotary knob. The main keypad functions include current setting, power setting, resistance setting, load control, program storage, program recall, program start, program stop, and menu access.

CC: Constant current mode draws the selected current as input voltage changes, within the instrument’s operating limits.
CP: Constant power mode adjusts current as voltage changes so the programmed power remains approximately constant.
CR: Constant resistance mode draws current in proportion to the applied voltage, simulating a selected resistance.

The 3700 Series Programmable DC Electronic Load can also be connected in parallel when a test requires greater combined loading capacity and the installation is designed appropriately.

Safety

Only trained and qualified personnel should install, operate, service, or repair this equipment. Read the operating instructions before applying power or connecting a test source.

Dangerous voltage may be present inside the enclosure. Do not remove covers during normal operation.
Connect the instrument through a three-conductor AC power cable with a firmly connected protective earth.
Verify that the rear-panel voltage selection matches the local AC supply before switching on the unit.
Keep the front-panel power switch off while connecting the AC cable and the device under test.
Do not touch internal components while the instrument is connected to power. Hazardous voltage can remain after disconnection.
Before internal service, disconnect the AC supply, remove external voltage sources, and discharge connected circuits.
Do not substitute parts or make unauthorized modifications, because these actions can compromise protective features.
Use only the correct fuse type and rating shown beside the rear-panel power input. The manual specifies a fuse within the 0.3 to 0.5 A range.

Setup and Operation

Connecting the Power

Confirm that the rear-panel voltage selector is set for the available AC supply.
Make sure the front-panel power switch is off.
Connect the supplied power cable to the AC input and to a properly grounded outlet.
Connect the DC source to the electronic load using suitable conductors and polarity.
Switch on the instrument and allow the display to initialize.

Setting Constant Current

Press I-set, enter the desired current with the numeric keypad, and press I-set again to confirm. The rotary knob can also adjust the value. Use the left and right keys to move the cursor between digits before turning the knob.

If keyboard protection is enabled, enter the four-digit password and press OK before changing the value. Press ESC to leave the setting screen without completing the operation.

Setting Constant Power

Press P-set, enter the required power, and press P-set to save the setting. In constant power mode, the load increases current when voltage falls and reduces current when voltage rises, subject to the model’s power and current limits.

Setting Constant Resistance

Press R-set, enter the resistance value, and press R-set to confirm. In this mode, the current follows the applied voltage according to the programmed resistance.

Turning the Load On or Off

Use the Load On/Off key to enable or disable the input load. Confirm the intended mode and limit settings before turning the load on.

Creating a Dynamic Program

A program applies a sequence of load values for defined periods. Each program can contain up to 10 steps, and each step uses the selected current, power, or resistance mode.

Open Menu and select Program.
Choose constant current, constant power, or constant resistance.
Enter the number of steps to use.
Enter the load value and duration for each step.
Select one-time execution or repeat operation.
Press ESC to return to the main screen.
Press Start to run the sequence or Stop to end it.

Saving and Recalling Programs

To save a configured program, press Store, choose a memory location from 1 through 9, and press OK. To retrieve one, press Recall, select the stored program number, and confirm with OK.

Menu Settings

Maximum current: Sets the upper current limit.
Maximum power: Sets the upper power limit.
Minimum input voltage: Turns the load off when the source falls below the selected threshold. This is useful for preventing excessive battery discharge.
Baud rate: Selects 4800, 9600, 19200, or 38400 bps for serial communication.
Address: Assigns a communication address from 0 through 254.
Knob enable: Enables or disables the rotary control.
Save option: Saves the last current, power, and resistance settings for automatic restoration at the next startup, or leaves this function disabled.
Key lock: Protects load settings with a four-digit password.
Load default: Restores factory parameter settings.
Exit: Leaves the menu.

Computer Control

The ElectronicLoad application can monitor and control the load through an appropriate RS-232, RS-485, or USB connection. The software supports load-mode selection, current, power and resistance settings, program creation, live voltage and current curves, data recording, and report export.

Connect the instrument to the computer using the appropriate interface adapter.
Install the ElectronicLoad application from the supplied software media.
Register or select the connected load in the software.
Set the computer’s communication port, baud rate, and load address to match the instrument.
Start communication and select PC control mode.
Return the unit to self-control mode before closing the application if front-panel operation is required afterward.

The software’s program window supports a maximum of 10 steps, allows only part of a stored sequence to run, and provides one-time or repeating execution. The recording interval can also be configured for measured data.

Troubleshooting

The load does not respond to the keypad: Check whether keyboard lock is enabled and enter the correct four-digit password.
The input turns off during battery testing: Check the minimum input-voltage setting. The load intentionally disconnects when the source drops below that threshold.
A program will not start: Confirm that a valid mode, step count, load value, and duration have been entered. Verify that the program is not stopped and that the load is enabled.
The computer cannot communicate with the load: Check the cable or adapter, selected COM port, baud rate, and instrument address. The settings must match on both sides.
Front-panel control is unavailable after using the software: Reopen the control selection and return the unit from PC control to self-control mode.
The fuse has opened: Switch off and disconnect the AC supply before replacement. Install only a suitable fuse matching the rear-panel marking and investigate incorrect voltage selection before reuse.
The displayed result appears outside the expected range: Confirm that the source polarity, operating mode, current limit, power limit, and connected wiring are correct.

Pros & Cons

Pros

Supports constant current, constant power, and constant resistance testing.
Accepts up to 360 V and 30 A, with 150 W or 300 W model options.
Offers programmable dynamic testing with stored multi-step sequences.
Includes protection for overvoltage, overcurrent, overpower, overheating, and reversed polarity.
Provides both front-panel operation and computer-based control.
Uses a backlit display, numeric keypad, and rotary adjustment control.

Cons

The 3710A and 3711A have different power limits, so the model must be selected carefully for the application.
Computer control requires the correct communication adapter and matching port settings.
Internal servicing involves hazardous voltages and is not suitable for unqualified users.
The instrument requires careful attention to AC voltage selection and fuse specification before operation.

PDF

Faqs

How should the 3700 Series Programmable DC Electronic Load be connected before power-up?

First confirm that the rear-panel voltage selector matches the available AC supply. Keep the front-panel power switch off while connecting the supplied three-conductor power cable, and use a properly grounded outlet. Connect the DC source to the load input with the correct polarity and secure wiring before enabling the load. Verify all connections carefully, because the instrument can handle hazardous voltage and current levels during operation.

What safety precautions are required when operating the 3700 Series electronic load?

Only qualified personnel should operate, commission, ground, or service the 3700 Series electronic load. Keep the protective earth connection intact and never remove the instrument cover during normal use. High voltage may be present inside the enclosure and at connected circuits, even after power is removed. Before servicing, switch off the instrument, disconnect the AC supply, remove external sources, and discharge connected circuits.

How do I select constant current, constant power, or constant resistance mode?

Use I-set for constant current, P-set for constant power, or R-set for constant resistance. Enter the required value with the numeric keypad, or adjust individual digits with the rotary knob and arrow keys, then press the corresponding setting key to confirm. Constant current maintains the selected current, constant power changes current as voltage changes, and constant resistance draws current approximately in proportion to input voltage.

How can the minimum input voltage setting protect a battery from over-discharge?

Open the Menu and select Min Input Volt, then enter the voltage at which the load should stop and confirm with OK. When the battery voltage falls below this programmed threshold, the 3700 Series automatically switches the load off. This function is useful for battery testing because it prevents continued discharge after the selected cutoff level is reached. Choose the threshold according to the battery and test requirements.

How do I create and run a dynamic load test program?

Open Program from the Menu, choose constant current, constant power, or constant resistance mode, and specify the number of steps. Enter the load value and duration for each step, then select one-time or repeat operation. Press Start to run the completed sequence and Stop to end it. A program can contain up to 10 steps, and completed programs may be stored for later recall.

What should I check if PC control of the 3700 Series electronic load does not work?

Confirm that the communication adapter and cable are firmly connected and that the software uses the same communication port, baud rate, and address configured on the instrument. The valid load address range is 0 to 254. Start communication in the software, select the correct load, and switch the instrument to PC control. If control remains unavailable, check that the selected model and registered load settings match the connected unit.

What should I do if the electronic load stops unexpectedly during a test?

Check whether a protection condition has occurred, such as over-voltage, over-current, over-power, over-temperature, or reversed input polarity. Also verify that the programmed minimum input voltage has not been reached, particularly during battery testing. Turn the load input off, remove the source if necessary, and inspect polarity, wiring, and programmed limits before restarting. Do not continue operation if abnormal heating, damage, or unsafe voltage is present.

How do I replace the fuse in the 3700 Series electronic load safely?

Switch off the AC power and disconnect the instrument from the outlet before replacing the fuse. Ensure that no other equipment remains connected, then use a small flat screwdriver to release the fuse holder on the rear panel. Install only a suitable fuse within the specified 0.3–0.5 A range and follow the rating marked beside the power input. Never substitute an incorrect fuse, as this can damage the instrument or reduce protection.