TTi QPX1200SP – 1200W ‘PowerFlex’ Power Supplies

• RS232, USB & LAN interfaces
• Single or dual outputs, 1200 watts total
• PowerFlex design gives variable voltage/current combinations within a power envelope
• Up to 60 volts or 80 volts and up to 50 amps
• Setting by direct numeric entry or by spin wheel
• High setting resolution of 1mV in up to 60 volts

The QPX1200S is a 1.2kW single output dc power supply that offers users a level of flexibility that cannot be achieved with conventional laboratory power supplies. It is suited to be bench-top and system applications and is fitted with both front and rear terminals and an analog remote control interface.

The QPX1200SP adds a wide range of digital interfaces: USB, RS232 and LXI compliant LAN (Ethernet). * Note that the QPX1200L (now discontinued) is identical to the QPX1200SP.

The QPX1200S is a different type of laboratory power supply designed to meet the need for flexibility in the choice of voltage and current. A conventional PSU has a fixed current limit giving a power capability that reduces directly with the output voltage.

The TTi PowerFlex design of the QPX1200S enables higher currents to be generated at lower voltages within an overall power limit envelope. Each output can provide three times the current of a conventional PSU of the same maximum voltage and power (see power curve).

Example voltage/current combinations include 60V/20A, 48V/25A, 37.5V/30A, 26V/40A, and 20V/50A.

The PowerFlex regulator includes a linear output stage giving the QPX1200S exceptionally low output noise for a unit of this power, and ensuring good transient response.

The QPX1200S is housed in a 350mm (13¾”) wide case suitable for use on the bench-top. Output and remote sense terminals are mounted both on the front and on the rear panel along with the analog and logic interface connectors and, on the QPX1200SP, the bus interface connectors. The power supply is 3U high and a rack mounting kit (RM310 or RM310A) is available as an option.

Power Calculation

The meter for each output can be set to show the total power currently being provided to the load (V x A) to a resolution of 0.1 watts. The power is shown in addition to the voltage and current values.

Low Resistance Calculation

The meter for each output can be set to show the equivalent resistance of the load by displaying voltage divided by current.

Low resistance measurements using a DMM utilize a low excitation current and suffer from thermal emf errors and other low voltage effects. This function enables low resistance measurements to be made at high currents by using the remote sense terminals to create a four terminal connection.

This can give much more reliable results for certain component types, such as magnetics, which operate at ampere levels.

Graphic Display For Clarity and Ease of Use

The QPX600D incorporates two high resolution graphic LCDs capable of showing numbers and text in a variety of sizes. The standard display mode shows voltage and current in large characters along with text annunciators such as CV mode and Output On.

When settings are being changed, a dual display of parameters is used enabling existing and new settings, or actual and limit values to be viewed simultaneously.

More complex functions are provided with text prompts or complete selection menus.

Current Meter Averaging

When measuring rapidly varying loads it can become difficult to get useful readings from the current meter. By selecting meter averaging, the reading is stabilised by averaging the last four readings to reduce the speed and extent of the variation.

Numeric or Rotary Entry

Voltage and current levels can be set directly via the numeric keypad. Alternatively settings can be changed via the jog wheel at user selectable increments.

Multiple Settings Stores

Non-volatile stores are incorporated for rapid recall of voltage and current settings and are useful for repetitive testing applications. Separate stores are provided for each output.

OVP and OCP trips

Variable trips for over-voltage and over-current are provided on each output. Unlike a limit setting, the trip setting turns the output off and provides a different level of protection. For example, when repetitively testing a unit which normally takes a peak current of 10A, the current limit could be set to 11A and the OCP to 10.1A to ensure that a faulty unit will trip the supply off and not be damaged by over dissipation. The output trip can also be activated by other fault conditions including over temperature and remote sense mis-wiring. The cause of the trip is shown on the display.

Both models incorporate analog interfaces for voltage control of both output voltage and output current (non-isolated)

The control voltages are digitized to control the PSU and the scaling can be selected as 0 to 5V or 0 to 10V for zero to full scale. Monitor outputs for voltage and current are also provided, and can similarly be selected as 0 to 5V or 0 to 10V.

An opto isolated logic control signal is provided for control of output on/off. This can be menu selected as true = output on, or true = output off. An opto isolated open-collector logic output signal is also available. This can be menu selected as true or false for output enabled or disabled, current limit, power limit, or any fault trip.

To meet a wide variety of needs, the QPX1200SP adds a comprehensive array of digital bus interfaces. RS-232, USB and LAN (Ethernet) with LXI support are all provided as standard. Each of the digital bus interfaces provides full control of voltage, current, output on/off and set-up, plus read-back of voltage, current and status. The interfaces are at ground potential and are opto-isolated from the output terminals.

An RS-232/RS-423 interface is provided for use with legacy systems. This type of serial interface remains in common usage and is perfectly satisfactory for the control of power supplies because data speed is not an issue.

USB provides a simple and convenient means of connection to a PC and is particularly appropriate for small system use. A USB driver is provided which supports Windows 2000, XP , Vista and Windows 7

The LAN interface uses a standard 10/100 base-T Ethernet hardware connection with ICMP and TCP/IP Protocol for connection to a Local Area Network or direct connection to a single PC. This interface supports LXI and is highly appropriate for system use because of its scalable nature and low cost interconnection.

The LAN interface is compliant with LXI class C. LXI (LAN eXtensions for Instrumentation) is the next-generation, LAN-based modular architecture standard for automated test systems managed by the LXI Consortium.

An IVI driver for Windows is included. This provides support for common high-level applications such as LabView*, LabWindows*, and HP/Agilent VEE*.

• LabView and LabWindows are trademarks of National Instruments. HPVEE (now Agilent VEE) is a trademark of Agilent Technologies.
• Windows is a trademark of Microsoft.