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Custom power supply solutions: DC power/energy absorber test system

Written on November 16, 2017 at 6:52 am, by

When one of our standard products cannot completely satisfy your requirements, AMETEK Programmable Power can design a custom power supply system for you. The solutions range from OEM integration for medical and semiconductor industries to modular avionics ATE power subsystems to turnkey solar array simulators for satellites. We also can modify our standard power supplies to meet your application requirements.

An example of what we can do is the Energy Absorber Test System that we recently built. The system can supply up to 400 VDC and sink up to ±150 A. The system hardware includes:

  • an AC distribution and interlock system,
  • DC power supplies,
  • an absorber load chassis, and
  • an energy absorber control chassis.

This custom test system can supply up to 400 VDC and sink up to ±150 A.

AC Control and Distribution

The power rack system includes an AC distribution system. With a DC output power rating of 60kW at 480VDC and 150A, the AC input current to the rack is 120A per phase with a 400VAC, 3 phase, 4 wire connection. AC power to the racks is through two pin and sleeve type connectors and routed through circuit breakers and the mains disconnect interlock contactors. The AC interlock operates by energizing relays which are operated by ON/OFF switch closures located on the front panel or with auxiliary switch closures which are available through a rear I/O panel connector. The ON/OFF panel contains two pushbutton switches, an ON pushbutton and a twist to lock OFF button. A door interlock and single point ground connection are also provided.

DC Power Supplies

The system uses Sorensen SGI and SGA Series power supplies, both of which can supply 0-400 VDC at 75 A. The SGI supply is the Master supply and can be operated remotely via GPIB or with front panel controls in local mode.

The SGA supply is used as a Slave, operating as a voltage controlled current source. This combination can supply up to 400V at 150A for 60kW of output power. By operating in a Master/Slave configuration, the supplies operate as one unit that can be controlled from the Master unit through either local control or IEEE-488 operation.

DC output is through an MS type connector of suitable type and ampacity on the rear panel. A mating connector is provided.

Energy Absorber Load Chassis

The Energy Absorber Load Chassis houses the regenerative resistive load element, which consists of numerous high power resistors connected in series/parallel banks. The energy absorber can dissipate 30 kW continuous and 60 kW peak.

Energy Absorber Control Chassis

The Energy Absorber Control chassis contains primary and secondary voltage clamps consisting of an IGBT and an SCR. In addition, it contains a GPIB controller and measurement circuitry and controls that provide drive signals to the power components. For more information on how the energy absorber works, download the product’s data sheet.

Communication

A GPIB interface allows users to remotely control the power supply outputs and read voltage and current measurements using standard SCPI commands. The Energy Absorber chassis includes a GPIB interface for programming the regen clamping limit, input contactor closure, dropout relay closure and voltage and current measurements. A GPIB connection is provided on the rear of the rack for both interfaces.

This is just one example of the many types of custom systems that AMETEK Programmable Power can design for you. If you would like more information about our custom capabilities, or to discuss your application, contact AMETEK Programmable Power by sending email to sales.ppd@ametek.com or phoning 800-733-5427.

Frequently-asked questions about the Sorensen DLM 600 Series

Written on October 19, 2017 at 10:52 am, by

The Sorensen DLM 600 series of programmable power supplies is designed to provide continuously variable output voltage and current for a broad range of applications in a compact 1U (1.75 inches) high, half-rack (8.5 inch) wide chassis.

The Sorensen DLM 600 series of programmable power supplies is designed to provide continuously variable output voltage and current for a broad range of applications in a compact 1U (1.75 inches) high, half-rack (8.5 inch) wide chassis. The DLM 600 power supply series is ideal for high density, multiple output, rack-mount applications or low profile benchtop applications. Output voltages from 0-5 VDC to 0-300 VDC and currents from 0-2 A to 0-75 A are available.

Here are some of the most frequently-asked questions about this power supply line:

1. What is the AC input voltage of the DLM600 series of power supplies?

The DLM600 power supply uses an automatic input voltage selector and will operate between 90 to 132VAC or 180-264VAC single phase.

2. Can the DLM600 series of power supplies be operated in parallel?

Yes, these supplies can be operated in parallel using the DLMP1 paralleling cable. The Master unit must have the set-up switch position –2 set (Master/Slave) set to OFF (down) and the Slave unit must have the set-up switch position –2 set to the ON (up) position.

3. Can we install the GPIB (IEEE-488) interface option after purchase?

Yes, however because of some special equipment required to complete the alignment process, it is recommended that this option be installed at the factory.

4. Can we install the Ethernet interface option after purchase?

Yes, however because of some special equipment required to complete the alignment process it is recommended that this option be installed at the factory.

5. We need isolated analog controls to safely operate the DLM600 power supply. Is there such an interface available?

Yes, we do offer an isolated analog interface for controlling the power supply and reading back the output monitor signals.

6. Can the DLM600 powers supplies be connected in series for higher output voltages?

Yes, the DLM600 supplies can be connected in series. To use the remote analog control and readback capabilities, however, the Isolated Analog interface option is required.

7. Can the DLM600 be used to test motors?

Yes, but to test inductive loads, such as a motor, a blocking diode and a freewheeling diode on the output are recommended.

8. Can the DLM600 power supply be used to charge batteries?

Yes, but a blocking diode on the output of the supply is required to prevent damage to the supply if it shuts off while connected to a battery.

9. Can the DLM600 Series power supply be remotely programmed?

Yes, the standard unit offers remote analog programming capabilities using 0 to 5 volt or 0 – 10 volt signals. Refer to the operators’ manual on the CD supplied with the supply or download a copy from our website.

10. Can the DLM600 series be rack mounted?

Yes, the DLM600 can be rack mounted using the rack mount option kit. Please request this option when ordering the supply or contact Ametek Programmable Power sales for ordering this kit for supplies you have already.

11. Is technical support available for this product?

You can contact AMETEK Programmable Power for sales and technical support for any of our products by sending email to sales.ppd@ametek.com or phoning 800-733-5427. When calling, please have the full model number and serial number as printed on the unit’s ID label (not on the unit’s faceplate). The numbers on the ID label indicate options and/or modifications that may have been installed on the supply; without this information there may be a delay or a wrong answer in obtaining technical assistance.

Benchtop power supply features ensure DUT safety

Written on September 26, 2017 at 9:03 am, by

Everyone’s under pressure these days to get results. So, there’s nothing worse than getting your bench test all set up, throwing the switch, and watching some of the magic smoke escape because of some setup error. To prevent this from happening when you’re under pressure, you need the Sorensen XBT 32-3FTP True Triple Output Digital Benchtop Power Supply.

The Sorensen XBT32-3FTP (see right) is a 16-bit triple output supply. Channels 1 and 2 can be programmed 0-32V and 0-3A each. The third output is fully programmable 0-15V, 0-5A up to a maximum of 30W. Channels 1 and 2 can be configured for tracking, parallel or series operation to, in effect, provide the equivalent of 6 different power supplies. In isolated mode, each of the 3 outputs functions independently; in tracking mode, channels 1 and 2 provide the same, but isolated output; in parallel mode, there is one 0-32V/0-6A output and one 0-15V/0-5A/30W output; in series mode, there is one 0-64V/0-3A output and one 0-15V/0-5A/30W output.

The Sorensen XBT32-3FTP benchtop power supply provides superior device under test (DUT) protection. Each output is fully isolated, and users can preview the voltage and current settings before turning on the outputs. This allows users to double check the settings before applying power to a valuable prototype.

The built-in output switches, in addition to enabling the preview mode, allow users to configure the outputs for parallel or series connection. When a user configures the supply’s output for parallel or serial connection, graphics on the front panel show the user how to make connections. This helps eliminate mistakes that could inadvertently destroy a DUT.

Other features that promote DUT safety include:

  • Configuration memory. The XBT can store up to 100 different configurations. Storing configurations in memory can help prevent set up mistakes which could damage a DUT.
  • Output timer. The built-in output timer can be set from one second to 100 hours. When the timer times out, the XBT turns off its outputs.
  • Power-on state and synchronous or individual control of each channel output. This is important when voltages supplied to a DUT must be applied in a particular sequence.
  • Over-voltage protection (OVP) and over-current protection (OCP). Users can program the OVP and OVC values separately for programmed for each output. OVC and OVP prevents a faulty DUT from drawing too much current that could cause subsequent damage to the device.

In addition to these safety features, the XBT offers all of the other features that you’d expect from a professional benchtop power supply, including excellent line and load regulation and remote operation via Ethernet, USB, GPIB, and RS-232 interfaces. For more information on Sorensen benchtop power supplies, contact AMETEK Programmable Power by sending email to sales.ppd@ametek.com or phoning 800-733-5427.

Asterion makes harmonic analysis easy

Written on September 25, 2017 at 12:07 pm, by

Power systems operate at frequencies of 50 or 60Hz, but some devices, including personal computers, printers, and some industrial equipment, present a non-linear load and create currents and voltages with frequencies at harmonic frequencies. These harmonics get fed back into the power system and can cause other devices connected to the power source to malfunction. There are several standards that specify the level of harmonics that a particular device can produce.

The Asterion Series power source makes it easy to determine the harmonic content produced by a device under test (DUT). It uses advanced digital signal process (DSP) techniques to digitize its output voltage and current waveforms, and then perform a harmonic analysis of the data. To do this, the Asterion Series performs a fast Fourier transform (FFT) on both voltage and current. The resulting frequency spectrum (DC through 49th harmonic) can be displayed on the LCD display in a tabular as well as a graphical format. 

Acquiring FFT data

To perform an FFT analysis on the output of the power source, you must first acquire data. Using the front panel display, you perform the following steps:

  1. Navigate to the HARMONICS menu of the MEASUREMENTS screen.
  2. Scroll to the FUNCTION field and select VOLT or CURRENT.
  3. Scroll to the VIEW field and select the TABLE or BAR display mode.
  4. Scroll to the DATA field and select ABSOLUTE or RELATIVE. The ABSOLUTE display format will show all harmonic components in volts or amps. The RELATIVE display format will use the fundamental as a 100% reference and display all harmonics as a percentage of the fundamental. Phase angles are always shown with respect to the fundamental frequency.
  5. Tap the MODE field and select SINGLE or CONTINUE. The SINGLE mode will acquire the data once and show the result, while the CONTINUE mode will update the data continuously.
  6. Tap the SOUR field and select IMMEDIATE; alternate trigger mode is PHASE.
  7. Tap the START field to start the analysis. The display mode that was selected will be opened and the results displayed. If the trigger mode, CONTINUE, was selected, the data will be continually updated.
  8. Returning to the HARMONICS menu can be done by tapping the UP arrow button. To display the data in a different format, the selections are changed as desired, and a new acquisition started by tapping the START field.

 

Analyzing FFT data

Once you have acquired the data, you can analyze the data. The Asterion will perform a FFT analysis on the data and display the entire data set using either tabular or graphical formats. For tabular display, as shown in the figure below, the Asterion shows harmonics in five groups with ten harmonics per group. You use the LEFT and RIGHT arrows to scroll through the data vertically.

You can also display the FFT data in bar chart format as shown in the figure below.

In this display, the Asterion shows only the amplitude information graphically. The phase data is displayed in numeric format at the right-side of the display. The display can show up to 25 harmonic components at a time. The triangle at the bottom of the display shows the currently selected component for which numeric data is shown on the right-side. This data includes the harmonic number (DC through 50), the harmonic frequency, the absolute or relative amplitude (depending on selection in DATA field), and the phase angle with respect to the fundamental. The rotary encoder could be used to scroll through the displayed harmonics horizontally, or the touch-screen could be used to directly select an individual harmonic.

You can, of course, also access these measurements via the remote digital interface using the Asterion Virtual Panels or SCPI commands. This capability allows you to do more in-depth analyses as well as automate harmonic analysis tests. For more information on the Asterion Series, contact AMETEK Programmable Power by sending email to sales.ppd@ametek.com or phoning 800-733-5427.

Know Your Power Supply Jargon: Regulation

Written on September 3, 2017 at 6:23 am, by

The Sorensen XG 1500 Series is an industry leading programmable DC power supply designed for test, production, laboratory,OEM and quality assurance applications. The XG 1500 is a 1500 Watt, 1U programmable power supply with constant voltage and constant current modes, automatic cross-over and numerous features enabling cost effective,easy integration.

The most important thing that a power supply does is to maintain a constant voltage output or a constant current output. This is true whether the power supply is built into a product and provides fixed output voltages, such as a desktop computer power supply, or a power supply that is on the test bench or is part of an automated test system that must provide variable outputs. We call this ability to maintain a constant output voltage or current regulation.

Load regulation

There are actually two types of regulation that you need to be aware of when selecting a power supply: load regulation and line regulation. Load regulation is the ability of a power supply to maintain a constant output voltage (or current) under under very light loads and under loads near the maximum current. That is to say that if you set the output voltage of a supply to say 10 VDC, the supply should be able to maintain its output at 10 VDC when no current is being drawn from the supply and when the maximum current is being drawn from the supply.

To see how this might work in practice, let’s take a look at the Sorensen XG 12.5-120, one of the supplies in the XG 1500 Series. It can supply up to 12.5 VDC at currents up to 120 A. The load regulation for the XG 1500 Series is specified to be 0.005% of rated output voltage + 2 mV. For a 10 V output, that works out to be 2.5 mV, from no load to 120 A.

Line regulation

The calculations for load regulation assumes that the AC input voltage will remain constant. Of course, this is not always the case. AC line voltage can change, and this can also affect the output of a power supply. The ability of a power supply to maintain a constant output voltage when the input voltage changes is called line regulation.

The line regulation for the XG 1500 Series is also 0.005% of rated output voltage + 2 mV, assuming a constant load. For a 10 V output, that works out to be 2.5 mV, with an input voltage of 85-132 VAC for the nominally 110 VAC model, or an input voltage of 170-265 VAC for the nominally 220 VAC model.

Load and line regulation aren’t the only specifications that affect a power supply’s output. In some applications, for example, transient response time is also important. Load and line regulation are baseline specifications, though. Without good line and load regulation, the other specifications are meaningless.

For more information on DC power supplies, and how to use them in your application, contact AMETEK Programmable Power. You can send an e-mail to sales.ppd@ametek.com or phone 800-733-5427.

Sorensen SG Series ensures auto parts reliability

Written on August 28, 2017 at 7:31 am, by

One of the big challenges when designing and manufacturing auto parts is ensuring that they operate reliably in very hot environments, such as Dubai, where the high temperature can easily reach 40˚C. Of course, they must also operate reliably in very cold environments, such as Siberia, where the thermometer can drop to -40˚C or below. You certainly don’t want parts to fail when you’re zipping down the road at 200 km/hr. because they can’t take the heat (or the cold).

To ensure that their products don’t fail, most supplier will perform some kind of environmental testing. They will place the parts in an environmental test chamber and simulate the environment in which the component must operate. A computer is used to put the component through its paces while in the chamber.

The manufacturer of the electrically-powered, steering belt drive shown above designed just such a test. This drive features a modular design and can be used in vehicles as small as C-segment vehicles and as large as full size trucks. It can handle rack loads as high as 18kN and features a fully integrated steering gear that can be mounted in either inboard or outboard configurations.

The test system for this drive included:

  • An environmental test chamber capable of producing ambient temperatures as high as 85˚C and as low -40˚C. The chamber also has humidity control that enables it so simulate a wide range of operating environments.
  • A 19-in. rack to house the test system instrumentation.
  • A rack-mounted Sorensen SGA 20x500D DC power supply, with a GPIB interface, to supply power to the device under test (DUT).
  • Rack-mounted instrumentation required to monitor the output of the electrically-powered, steering belt drive’s sensors.
  • A rack-mounted computer running a test program to control the environmental chamber and the Sorensen SGA power supply. The computer simulates the drive’s ECU (Electronic Unit Control), sending commands to the drive’s actuators and measuring the drive’s sensor outputs. In addition to running the test, the computer outputs a test report once a test run is complete.

While a number of different temperature profiles is available with this system, a typical profile would look like the following:

  1. 23˚C for 30 minutes.
  2. -40˚C for six hours
  3. 85˚C for 70 hours

At these temperatures, the computer will run a series of performance tests to ensure that the drive will operate reliably at these temperatures. During the course of these tests, the DUT power supply voltage can also be varied to test the drive’s sensitivity to input power variations.

In most automotive applications, it is not necessary to use a DC power supply with fast rise and fall times, but a programmable power supply is a must to test input voltage sensitivity. The Sorensen SG Series is a good choice because they have a wide range of voltage and current capabilities which allow you to choose the model that’s right for your application. They also have very stable outputs, which is important because tests can last a long time.

For more information on how you can use Sorensen DC power supplies and other AMETEK Programmable Power products in automotive applicatons, contact AMETEK Programmable Power. You can send an e-mail to sales.ppd@ametek.com or phone 800-733-5427.

How electronic loads work

Written on August 22, 2017 at 8:18 am, by

Electronic loads are used in a variety of tests, including power supply tests and battery tests. You can program them to provide exactly the kind of load that you need for the device you are testing.

One of the most common ways to use an electronic load is in the constant current (CC) mode. In this mode, the electronic load will draw a constant current from the device under test (DUT), no matter what the output voltage is. The figure below shows a simplified schematic of an electronic load to illustrate how the CC mode works.

Current from the device under test flows through both the power FET and the current shunt resistor. The voltage across the shunt resistor is compared to a voltage reference and the difference between the two is used to control the drain-to-source resistance, RDS, of the power FET. If the load current is higher than the desired constant current, the circuit will adjust the FET’s gate voltage to increase RDS and thus reduce the load current. If the load current is lower than the desired constant current, the circuit will adjust the gate voltage to reduce RDS, and the load current will increase.

In an actual electronic load, VREF is supplied by a digital-to-analog converter (DAC). The user sets the DAC output voltage to yield the desired constant-curent level. The CC accuracy specification is largely determined by the accuract of the digital-to-analog converter used in this circuit.

Constant-voltage mode

Most electronic loads also offer a constant-voltage (CV) mode. In this mode, the electronic load will maintain a constant voltage across the device under test. You would use this mode to test a battery charging circuit. The figure below shows a simplified schematic for an electronic load operating in constant-voltage mode.

In CV mode, the feedback signal is generated by a precision voltage divider. This signal is again compared to a voltage reference, and the output of the comparator is used to increase or decrease the RDS of the power FET. This basically changes the input impedance of the electronic load, allowing it to maintain a constant voltage across the input terminals, no matter how much current it is sinking.

Just like the CC mode, VREF is normally supplied by a digital-to-analog converter. Changing its output will change the CV value.

Modern electronic loads also offer constant-resistance (CR) and constant-power (CP) modes. The circuits used to implement these modes are usually some variation of the circuits used for the CC and CV modes. For more information on how electronic loads work, and how to use them in your applicaton, contact AMETEK Programmable Power. You can send an e-mail to sales.ppd@ametek.com or phone 800-733-5427.

Minimize noise from power supplies when making low-level measurements

Written on August 1, 2017 at 7:22 am, by

Low-level measurements are susceptible to noise from a number of different sources. While discussing all the ways that noise can degrade low-level measurements is outside the scope of this article, let’s at least consider how to make sure that your test system power supply is not a problem:

  1. Start with a low-noise power supply. The first step to ensuring that noise doesn’t affect your test system’s low-level measurements is to use a low-noise power supply. In general, linear power supplies are less noisy than switching power supplies, and this makes them a better choice for powering test systems that must make low-level measurements. The Sorensen XT Series, for example, has an output noise and ripple specification of less than 1 mV.
  2. Use shielded cable to connect the power supply to a load. You can minimize the radiated noise picked up by the power supply leads by using twisted-pair, shielded cable for both the output and remote sense leads, as shown in the figure below.

    Connect the shield to ground at one end only, preferably the single-point ground on the supply, as shown. Another thing that you can do to reduce noise pickup is to use a common-mode choke in series with the output leads and a shunt capacitor from each lead to ground.

  3. Avoid imbalances in load lead inductance. By using shielded, twisted-pair cable to connect the supply to the load, you ensure that the leads are the same length, which helps you avoid any imbalance in the leads. Directly connecting the cable to the DUT also helps you avoid any imbalance..
  4. Eliminate ground loops. Another way to minimize conducted noise is by eliminating ground loops. The system should have only one connection to ground. In rack systems, where you have multiple ground points, keep the DC distribution path separate from paths that carry other ground currents. If necessary, you can isolate the power supply from ground. The Sorensen XT Series offers isolated outputs that make this easy to do.
  5. Use a bypass capacitor at the load to smooth voltage spikes. If your load rapidly changes the amount of current drawn from the supply, it may cause voltage spikes. Adding a bypass capacitor close to the load will help reduce those spikes.. The capacitor should have a low impedance at the highest testing frequencies.

For more information on reducing noise in your test system, contact AMETEK Programmable Power. You can send an e-mail to sales.ppd@ametek.com or phone 800-733-5427.

Get the Rev Right When Running MIL-STD-704 Test

Written on July 25, 2017 at 1:46 pm, by

As noted in an earlier blog post, the tests you run to ensure that airborne utilization equipment is compatible with an aircraft’s power system are specified in a series of MIL-HDBKs, specifically MIL-HDBK-704-1 through MIL-HDBK-704-8. To run these tests, a sophisticated power source is essential to simulate various power conditions. In addition, you also need whatever equipment is required to monitor the unit under test (UUT) while running the test.

Recognized as a world leader in programmable power, AMETEK Programmable Power has provided test equipment for compliance tests for airborne utilization equipment for decades. Over the years, we’ve updated our systems to cover the latest versions of MIL-STD-704 and to make our test equipment more effective and easier to use. Our MIL-STD-704 test solutions are in use by customers in U.S. and in countries all over the world.

Rev. F doesn’t negate earlier versions

Although the latest version of MIL-STD-704 is rev. F, you may have to run tests that comply with previous versions of the standard. The reason for this is that aircraft platforms tend to have a long life, and the power systems in those aircraft may be designed to comply with an earlier version of MIL-STD-704. When testing the utilization equipment for a particular platform, then, it’s imperative that you know what revision of MIL-STD-704 that the aircraft platform was designed to comply with.

The early versions of MIL-STD-704 specified the requirements for fewer types of power systems than the later revisions. Rev. A, for example, described the requirements for only three aircraft electric power systems:

  • three-phase 115V/400Hz AC,

  • single phase 115V/400Hz AC for devices requiring less than 500VA, and

  • 28V DC.

In rev. B, the authors added requirements for the 270V power system.

In rev. F, there are specifications for seven different power systems. In addition to the four already mentioned, rev. F includes specifications the following aircraft electric power systems:

  • single-phase, 115V/360-800Hz various frequency,

  • three phase 115V/360-800Hz various frequency, and

  • single-phase 115V/60Hz to power commercial, off-the-shelf (COTS) equipment.

Figure 1. Select the MIL-STD-704 version as needed.

Because utilization equipment may have to comply with earlier versions of MIL-STD-704, AMETEK Programmable Power’s test solutions allow users to easily select the appropriate version of the specification when setting up the test. As shown in Figure 1, test engineers and technicians, simply choose the appropriate revision from a drop-down menu.

Figure 2. Select the appropriate power group.

The next step is to choose the type of power that the power source is to supply to the utilization equipment. This is done by selecting one of the power groups as shown in Figure 2.

MIL-HDBK-704-1 through MIL-HDBK-704-8 specify the acronyms used for the seven power groups. They are:

  • SAC (single phase 115V/400Hz),

  • TAC (three phase 115V/400Hz),

  • SVF (single phase 115V various frequency),

  • TVF (three phase 115V various frequency),

  • SXF (single phase 115V/60Hz),

  • HDC (270V DC), and

  • LDC (28V DC).

Once these have been selected, the power source will supply power that simulates the various operating conditions as specified in MIL-STD-704. These include normal, transfer, abnormal, emergency, electric starting and power failure conditions. When subjected to these power conditions, the utilization equipment is expected to operate normally and perform to specifications.

These documents, including MIL-STD-704 (revisions A through F) are available online at EverySpec.Com. For information on how to use AMETEK power sources to run MIL-STD-704, contact AMETEK Programmable Power. You can send an e-mail to sales.ppd@ametek.com or phone 800-733-5427.

Know Your Power Supply Jargon: Ripple

Written on July 14, 2017 at 8:06 am, by

AMETEK Programmable Power DC power supplies convert AC power to DC power. While our supplies are very good at doing this, they’re not perfect. On the output, there will be some small amount of AC still present. This is called ripple.

Minimizing ripple is important because excessive ripple because it can have adverse effects on the systems or circuits that a supply is powering. It can for example, cause measurement errors when a supply is powering instrumentation circuits or cause distortion when power audio circuits.

To see how ripple occurs, let’s take a look at a simple linear power supply. Linear supplies generally use a transformer to convert 120 VAC or 240 VAC mains power to a lower AC voltage. That AC voltage is then rectified to convert the AC to DC. A full wave rectifier will convert the AC voltage to the DC waveform shown as a dashed line in Figure 1.

To smooth that voltage we can put a filter capacitor across the output of the rectifier. It will charge when the rectified voltage is increasing and discharge when the rectified voltage is decreasing, but not discharge to zero. The voltage across the filter capacitor is shown as the orange line in Figure 1. The peak-to-peak value of the AC component of the voltage across the capacitor is the ripple voltage. The addition of a choke and a second capacitor to for a low-pass pi filter will reduce the ripple even more.

Of course, AMETEK Programmable Power supplies use much more sophisticated circuits to filter and regulate the output voltage. Our linear supplies, for example, use semiconductor voltage regulators to nearly eliminate ripple. The Sorensen XT Series, for example, has an output noise and ripple specification of less than 1 mV.

On most AMETEK Programmable Power data sheets, you’ll find noise and ripple combined into a single specification. Noise is any added and unwanted electronic interference, and it’s difficult to really differentiate how much of the unwanted output variation is due to ripple and how much is added noise. In switching power supplies, the measurement is given as a peak-to-peak voltage, indicating how much the output voltage can deviate from the nominal value.

For more information on power supply ripple, contact AMETEK Programmable Power. You can send an e-mail to sales.ppd@ametek.com or phone 800-733-5427.