The Farnell TOPS 3D is a triple output bench power supply designed to provide three independent power outputs with integrated digital meter monitoring for voltage and current. It is housed in a compact package, making it suitable for various benchtop applications.

Function Description

The TOPS 3D offers three distinct power outputs:

4-6V, 4A Output: This output is adjustable between 4 and 6 volts and can supply up to 4 amps. It features foldback current limiting and SCR overvoltage protection for enhanced safety. A single turn potentiometer is used for voltage adjustment.
-5 to -17V, 1A Output: This is one half of a bipolar tracking output, adjustable from -5 to -17 volts and capable of supplying up to 1 amp.
+5 to +17V, 1A Output: This is the other half of the bipolar tracking output, adjustable from +5 to +17 volts and capable of supplying up to 1 amp. Both bipolar outputs are adjusted simultaneously using a single 10-turn potentiometer, simplifying voltage setting.

Each of the three outputs is equipped with an independent ON/OFF switch and an LED indicator for current overload conditions. The internal digital meters allow simultaneous monitoring of voltage and current for any selected output by pressing the appropriate push button. Additionally, the voltmeter can be switched to measure external voltages up to 39.99V, isolated from the power supply output up to 200V d.c. or a.c.

Important Technical Specifications

Mains Input:

50/60Hz, 110, 220 & 240V ±10% by internal tap change.

Outputs:

4 to 6V at 4 amps.
Tracking -5 to -17V; 0; +5 to +17V at 1 amp.

Voltage Controls:

4-6V single turn potentiometer.
5-17V 10-turn potentiometer.

Line Regulation (Output change for ±10% supply input change):

Less than 0.05% output +2mV.

Load Regulation (Output change for zero to full load change):

4-6V output: less than 0.2% output +5mV.
17-0-17V outputs: less than 0.05% output +2mV.

Ripple and Noise (At full loadΔF = 80kHz):

Less than 2mV pk-pk.

Transient Recovery Time (Typical):

Less than 300µs for output to recover within 50mV following 10% to 100% load change of 1µs risetime.

Temperature Coefficient (Typical):

0.02% per °C.

Working Ambient Temperature:

0°C to 40°C.

Storage Temperature:

-20°C to 50°C.

Overload Protection:

Foldback current limiting on 4-6V output.
Current limiting on 17-0-17V outputs.
Additional protection offered by rear panel mounted fuses.

Overload Indication:

Onset of limiting indicated by LED mounted in OUTPUT ON/OFF switch bezel.

Overvoltage Protection:

SCR crowbar protection on 4-6V output only.

Meters:

4 digit LED VOLTMETER and 4 digit LED CURRENT METER.
Voltage and current simultaneously monitored on any one output selected by front panel push buttons.
Voltmeter only can be selected to measure external voltages.

Current Meter:

Display: 4 digit, 12.5mm, high output red LED.
Range: 0 to 3.999 amps (Overrange indicated by OFL).
Resolution: 1mA.
Accuracy: ±0.3% reading ±0.1% full scale at 23°C.
Damping: Switch selectable damping on ammeter to even out rapidly changing currents.

Voltmeter:

Display: 4 digit, 12.5mm, high output red LED.
Range: 0 to 39.99 volts (Overrange indicated by OFL).
Resolution: 10mV.
Accuracy: ±0.2% reading ±0.1% full scale at 23°C.

External Voltage Measurement:

By selection of three push buttons the voltmeter can be used to measure external voltages.
Range: 0 to 39.99 volts via 4mm front panel sockets.
Suitable plugs type Vero 63-1864C or similar.

Input Impedance:

1MΩ approximately.

Isolation:

Input sockets to voltmeter are fully isolated from power supply output terminals when operated in external mode.
The input terminals must not float at greater than 200V peak from chassis.

Dimensions (Approx Overall):

Height 169mm, Width 219mm, Depth 290mm.

Weight (Approx):

7.4kg.

Design:

Designed to meet IEC348/BS4743 safety requirements for electronic test & measuring apparatus.

Usage Features

Intuitive Controls: A 10-turn potentiometer for the bipolar outputs and a single-turn potentiometer for the 4-6V output make voltage setting straightforward.
Clear Monitoring: Large, bright LED displays provide clear annunciation of voltage and current for any selected output.
Ammeter Damping: A switch-selectable damping feature on the ammeter helps to stabilize readings when monitoring rapidly changing currents, reducing digit flickering.
External Voltage Measurement: The voltmeter can be used to measure external voltages up to 39.99V, offering versatility beyond just monitoring the power supply's own outputs. This feature is isolated, allowing the DVM to float up to 200V dc or ac peak from earth.
Safety Features: Preset current limits on all outputs, overvoltage crowbar protection on the 4-6V output, and LED indicators for overload conditions enhance operational safety.
Independent Output Control: Each of the three outputs has its own ON/OFF switch, allowing for flexible operation.

Maintenance Features

Accessible Fuses: The mains supply fuse and the three output fuses are all conveniently accessible on the rear panel for easy replacement.
Natural Convection Cooling: The unit is cooled by natural convection, eliminating the need for internal fans and reducing potential points of failure. Users are advised not to restrict airflow around the unit.
Voltage Tap Change: The instrument's operating voltage can be changed by adjusting internal transformer taps, allowing adaptation to different local mains supplies (110V, 220V, 240V). This procedure involves removing the top cover and base, and requires careful attention to safety instructions.
Recalibration Procedure: A detailed recalibration section is provided in the manual, outlining steps for adjusting voltage and current readings using potentiometers on the control board. This ensures the accuracy of the digital meters over time.
Repair and Recalibration: Repair and recalibration should only be attempted by qualified personnel. Farnell Instruments Limited offers repair and recalibration services, with contact information provided for both the Service Department and Regional Office.
Warranty: The equipment is guaranteed against defective material and faulty manufacture for a period of twelve months from the date of despatch. Farnell also ensures that all parts and components used in the equipment are manufactured to meet specified quality standards.
Damage in Transit: Clear instructions are provided for handling damage in transit or shortage in delivery, requiring immediate notification to carriers and Farnell Instruments Ltd. within five days of receipt.

Farnell TOPS 3D - Table of Contents

Table of Contents

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