Power Supplies

Introduction
Advantages of a Laboratory Benchtop Power Supply
Commercial Cooler Power Supply
Match TEC to Controller's Capability
Match Power Supply to Controller
Match Power Supply to TEC
Special Notes: Using Multiple Power Supplies
General Information About Power Supplies
Some Precautions and Warnings
POWER SUPPLIES PRICING
Additional Notes
   Using Multiple Power Supplies in Parallel

 
 

We do not recommend specific power supplies unless we are preforming the design and engineering of the entire project, however, here are some notes we put together about some power supply sources.

Note: "TEC" stands for Thermoelectric Cooler, which is a Peltier module.
 
 

For working with low power TECs we use a TENMA Laboratory DC Power Supply 72-2005. It has over current protection so that it shuts off if the current goes too high. It also has coarse and fine adjust with meters for the current and voltage. It is a nice general purpose power supply for up to about 20 vdc and 3 amps. There are other TENMA benchtop power supplies with more power. These are available from  Newark among others.

Your local electronics store may have TENMA or other power supplies.
 
 

If you are working with a commercial TEC based "cooler" (such as Igloo) it will have its own power supply. You may not be able to find the information you need, though, on the power supply or TEC. Be careful that you determine the operating voltage and the Imax (max current draw) and that these values match your temperature controller's capability.
 
 

These two examples use a Model 5R7-350 temperature controller: 9-24 vdc, 7.5 amperes max (heatsink recommended for 3A or more).

Note that the Model 5R7-350 requires at least 9 vdc for its own operation, but can be configured to use two power sources. For TECs that have a Vmax less than 9 vdc use one power source for the controller and a second for the low voltage TEC.

This first one is OK for the 5R7-350.

#1) Imax 3.1 amps, Vmax 15.7 vdc (OK. Heatsink recommended.)

#2) Imax 5.6 amps, Vmax 16.1 vdc (OK. Heatsink recommended.)

#3) Imax 5.6 amps, Vmax 7.9 vdc (OK. Heatsink recommended. Requires 2 power supplies.)

#4) Imax 2.7 amps, Vmax 12 vdc. (OK.)

You would need a more powerful controller, such as our Model 5R7-001 for this next one because of the higher Imax. Or, in the case of the 5R7-350 controller, you would need additional heatsinking for the controller.

#5) Imax 8 amps, Vmax 16.1 vdc (Amperage is too high for 5R7-350)

#6) Imax 12.4 amps, Vmax 15.9 vdc (Amperage is too high for 5R7-350)

So, the point is that you want to match the pelter specifications to the specifications of the temperature controller, or Vice-versa.

 
 

If you can run the load with the same voltage that is used to run the controller itself, a single output power supply will suffice.

Controllers such as the 5R7-001 can also run low voltage TE modules, but still require 12 or more volts for the controller itself. In this case you can use one power supply for the controller and one for the TEC, or dual output power supply. Usually the power supply for the controller would be 12 vdc and 1 amp - but the current draw is less than 500 milliamps, and the Model 5R7-350 can optionally go down to 9 vdc, and so smaller power supplies or even batteries could be used for the controller itself.

We can and do build controllers that run on 5 vdc or some other custom voltage or voltage range for our OEM customers.
 
 

The power supply must be able to supply the Imax of the TEC. It should be rated for the TEC's Imax or more.

The power supply must be able to supply "sufficient" voltage. It should be rated for the TEC's Vmax or less. It may be possible to have optimal operation of the TEC at 75% of the Vmax. A power supply with an adjustable voltage may be useful, especially for odd Vmax values such as 4.75 vdc.

If powering the controller and TEC from the same power output, add the requried milliamps of the controller to the Imax of the TEC to determine the power supply requirement.

Example:

For a module with these specifications:

Vmax 16.1 vdc
Imax 5.6 amps

We can run this with a controller from one power supply. If the controller requires 250 milliamps, we should add 0.25 amps to the Imax and that gives us 5.85 amps maximum.

So then, the power supply we select may be 12 to 16 vdc, with a capacity to handle 5.85 or more amperes.

 
 

We buy power supplies on-line and just about any will probably be OK. We have no particular recommendations, though. We use switching power supplies, not linear. They are generally lighter, less expensive, hold to the required voltage better, and dissipate less heat.

You need to multiply the voltage you are using by the maximum amperage that mght be drawn in order to determine the maximum watts required, and then use a power supply that is capable of supplying that many watts.

If a module has an Imax of 5A and a Vmax of 16v and if you are going to run it at 16v, then the power supply should be able to supply 5 x 16 = 80W or more.

Matching the right power supply (considering economics as well as power) is an area that requires some research and design experimentation on your part.

Some power supplies from other manufacturers may be smaller or lighter. Also, usually, the less power you need the smaller the power supply can be.

Note if they are single or multiple output, also. If you are going to run fans you may want a multiple output supply that also provides the VDC/AMPS needed for the fans.

When building a product for process control, note that 24 vdc is considered by some to be the current "standard" for industrial applications, and so you may want to consider using 24 vdc for the controller and TEC. If building a transportable product you may want to use 12 vdc, as provided by an automaobile battery, for the controller and TEC.
 
 

These precautions and warnings should not be used in lieu of those provided by the controller, TEC and power supply manufacturers.

1. Heatsink or Cool if Necessary: Be careful to note the cooling requirements of the power supply. You may see a power supply that provides the voltage and amperage you need but then there will be a note to the effect that the power supply requires certain ambient temperature conditions, or forced air cooling, or similar.
2. Supply Sufficient Amperage: Do not connect an output that sources less amperage than the the maximum current draw of the devices you are powering. If powering the controller and TEC add about 0.5 amps (check with us for the current draw of a specific controller model) to the Imax of the TEC to determine the maximum current draw you should allow for.
3. Supply Sufficient Voltage: Do not use a linear power supply for the controller unless you are sure it will provide the required voltage under load. For example, the 5R7-001 series of controllers require 12 vdc minimum for communications to operate normally.
4. Avoid Shorts and Sparks and Miswiring: Always have the supply power OFF when making or changing connections. Double-check your connections.
5. Prevent Thermal Runaway, Note 1: Have a thermometer or other way to test the TEC to see if the working side is heating when you expect it to heat, or cooling when you expect it to cool, so that you can be sure you hooked up the TEC with the appropriate polarity. If the TEC is hooked up with the wrong polarity you could experience thermal runaway and burn out the sensor or TEC or attached equipment/devices.
6. Prevent Thermal Runaway, Note 2: If your controller has a alarm settings with "power out shutdown if alarm" use this to prevent your TEC from thermal runaway.

 
 

We can supply the following Single Output Switching Power Supplies. Contact us for more information.

 

150 Watts
Dimensions: 199x110x50mm (5.1"x2.8"x1.3")

Model S-150-12: 12V, 0~12.5A, , (±10% DC adjustment range), 150W.
Model S-150-24: 24V, 0~6.5A, , (±10% DC adjustment range), 150W.

• AC input rangeselectable by switch
• Protections:Short circuit / Overload / Over voltage
• Fixed switching frequency at 25KHz
• Approvals: UL / CUL / TUV / CB / CE / BSMI
• Cooling by free air convection
• 100% full load burn-in test
• AC input voltage range......88~132VAC / 176~264VAC selectable by switch
• DC adjustment range......±10% rated output voltage
• Overload protection......105%~150% shut off, AC recycle to re-start
• Over voltage protection.....115%~145% rated output voltage
• Setup, rise, hold up time......100ms, 50ms, 28ms at full load and 230VAC
• Withstand voltage......I/P-O/P:3KVAC, I/P-FG:1.5KVAC, 1minute
• Working temperature......-10~60OC(refer to output derating curve)
• Safety standards......UL1012, UL60950-1, TUV EN60950-1 approved
• EMC standards......EN55022 class B, EN61000-3-2,-3 EN61000-4-2,3,4,5,6,8,11, ENV50204
• Connection......7P/ 9.5mm pitch terminal blockPacking    0.8kg ; 16pcs / 13.8kg / 0.95CUFT

 

320 Watts
Dimensions: 215x115x50mm (5.5"x3"x1.3")

Model S-320-12: 12V, 0~25A, , (±10% DC adjustment range), 320W.
Model S-320-24: 24V, 0~12.5A, , (±10% DC adjustment range), 320W.