A fixed overvoltage threshold of approximately 120% of the maximum rated output voltage is built into each output. Because the fixed overvoltage circuit is biased from the output terminals, it can be activated and provide protection even when the supply is not connected to the ac power line.

The OVRST command restores the programmed voltage and current values and clears the OV once the cause of the overvoltage has been eliminated.

OVERCURRENT--when the overcurrent protection feature is enabled, and the output is sourcing current and enters the

+CC operating mode, the output will be disabled (set to zero volts and minimum current) and the word OVERCURRENT will appear on the front panel display. In addition the OC status bit is set for that output. The OCRST command restores the programmed voltage and current values and clears the OC once the cause of the overcurrent condition has been eliminated. Refer to Chapter V for programming details.

UNREGULATED OUTPUT--the supply informs the user when output regulation is not guaranteed. This can occur when attempting to sink excessive currents below 2.5 volts or when operating outputs in parallel. The UNR annunciator on the front panel and the UNR bit in the status register indicate that the specified output is unregulated. Line voltage dropout or an incorrectly set ac power module can also cause the output to become unregulated. If line voltage dropout continues, the supply shuts down and will return to the power-up condition when normal line voltage is restored.

OVERTEMPERATURE--shuts down the linear pass and downprogrammer of the output that has reached an unsafe operating temperature. Operation of the other outputs is unaffected. An overtemperature can occur because of excessively high ambient temperature, a blocked fan, or insufficient space at the sides for adequate air circulation. When an overtemperature condition occurs, the word OVERTEMP appears in the front panel display and the OT status bit is set. This circuit resets automatically and restores the output approximately 30 seconds after the temperature drops sufficiently for safe operation.

ERROR--if the power supply receives an invalid command either through the front panel or the HP-IB, the ERR annunciator on the front panel comes on and the ERR bit in the serial poll register is set. The power supply does not execute the command and remains at previously set values. Pushing the ERR button in local mode displays the error message and clears the error. The error indicator may also indicate that an instrument failure has occurred. Refer to Appendix D for further details.

CONNECTING THE LOAD

Each terminal block cover on the rear panel is secured by a locking tab which snaps into a slot at the left of the terminal block. To remove, insert a screwdriver into this rectangular slot and move the locking tab to the left. When the locking tab releases, gently pull the terminal block cover away from the terminal block. To reinstall the cover, align it over the terminal block and gently press it into position until the locking tab engages.

SHOCK HAZARD Turn off ac power before making rear panel connections. All wires and straps must be properly connected with terminal block screws securely tightened. Replace terminal block covers before reapplying power.

Each rear terminal block has six M3.5 x 0.6 x 6 mm screws for attaching wires (see Figure 2-2). Load connections to the supply are made at the + V and -V terminals on each terminal block Do. not connect unterminated wires to the load terminals. Wires used for load connections must be properly terminated with termination connectors securely attached. Remember to replace the impact resistant plastic covers (HP P/N 06624-20007) over the terminal blocks after making connections.

46 Output Connections and Operating Information

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HP 6624A, 6623A, 6621A manual Connecting the Load
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6624A, 6621A, 6623A specifications

The HP 6623A, 6621A, and 6624A are precision DC power supplies widely recognized for their reliability and performance in various laboratory and industrial applications. These models are part of HP's 662X series, designed to cater to the needs of engineers, researchers, and technicians who require accurate power sources for their testing and development activities.

The main features of the HP 6623A, 6621A, and 6624A include their high stability, low ripple, and excellent load regulation, ensuring that the output voltage and current remain stable during testing. The power supplies provide multiple output channels, allowing users to power multiple devices simultaneously. The flexibility in setting voltage and current levels makes these models ideal for a wide range of applications, including semiconductor testing, device characterization, and system integration.

One of the standout technologies in the HP 662X series is the use of smart design techniques that minimize noise and enhance output performance. These power supplies incorporate advanced feedback mechanisms to maintain steady output, even under varying load conditions. Additionally, they feature programmable outputs, which means users can adjust the output levels through a connected computer or control system, streamlining the testing process and improving efficiency.

The HP 6623A model offers three independent outputs, with total power capabilities of 40 watts. It includes a 0-20V output, which can deliver up to 2A of current, along with two additional outputs that are adjustable. The 6621A provides a single output option, delivering a maximum of 20V and 2A, making it well-suited for simple applications where a single power source is required. In contrast, the HP 6624A stands out with its four independent output channels, providing a total of 60 watts, making it the most versatile of the three models.

Characteristics of these power supplies include user-friendly interfaces, allowing for easy configuration and monitoring of settings. LED indicators provide real-time feedback on voltage and current levels, enabling users to quickly assess the performance of their tests. Moreover, built-in protection features safeguard both the power supply and the connected devices from overvoltage and overcurrent conditions.

Overall, the HP 6623A, 6621A, and 6624A power supplies embody advanced engineering and design, making them invaluable tools for professionals looking for high-quality, reliable power sources for their electronic testing needs.
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