Last Updated: September 27, 2026
Quick Answer: A 24V TEC power supply for an industrial Peltier thermal-control panel must be selected from the complete operating envelope, not from the TEC module’s nominal wattage alone. For the WEHO MDR-100-24, the exact product photograph shows 24V/4A while the current family sheet lists 24V/4.16A. This article therefore uses a conservative 4.0A design boundary until the exact ordered revision is confirmed.
Thermoelectric systems can look electrically simple: apply DC power to a Peltier module and move heat from one surface to the other. A production panel is more complex. The supply may feed a TEC controller, H-bridge or PWM stage, fans, pumps, valves, sensors, indicators, and communications equipment. Current changes with thermal load, control direction, duty cycle, startup state, heat-sink performance, and ambient conditions.
For B2B selection, the useful question is not “Is this a 100W supply?” It is “Can the exact ordered model support the verified input, 24V load state, transient profile, thermal environment, interface, protection, and mechanical constraints?” This worked example shows how to answer that question without merging conflicting source values.
Reconcile the model evidence first
The enterprise-drive product image identifies the WEHO MDR-100-24. Its physical front label shows INPUT 100–240VAC, 1.3A, 50/60Hz and 24V/4A near the DC output terminals. The current MDR-100 family PDF identifies MDR-100-24 at 24V and 0–4.16A. The marketing caption beneath the source photo says 24V 4.2A.
Those values are close, but they are not identical. They may represent rounding, label artwork, or different revisions. The safe response is to keep them separate. For this article, the engineering screen is capped at the lowest clearly supported current—4.0A—until the purchaser confirms the ordered unit and applicable specification. Do not edit the product label, round the sheet upward, or present 4.2A as if all sources agree.
The current sheet documents an enclosure of 55 × 90 × 100mm and a nominal 24V variant efficiency of 86%. It also shows a six-position upper interface: two positive DC outputs, two negative DC outputs, and a two-position DC OK dry-contact output. The three lower AC positions are protective earth, neutral, and line. The dry contact is identified as a maximum 30VDC/1A interface; it is not a power output for the TEC load.
Build a state-based 24V load map
A TEC module can draw close to its maximum current for extended periods when the setpoint and environment create a large temperature difference. Meanwhile, heat-rejection fans or a pump may run continuously, and the control electronics still need stable power. Build the load schedule from the actual controller and module data.
An illustrative machine-vision enclosure could have this maximum concurrent state:
| 24V load group | Example current | Power at 24V |
|---|---|---|
| TEC controller and power stage | 0.25A | 6.0W |
| Peltier module at defined duty limit | 2.60A | 62.4 وات |
| Heat-sink fans | 0.25A | 6.0W |
| Condensate pump or valve | 0.15A | 3.6W |
| Sensors, alarms, and communication | 0.15A | 3.6W |
| Illustrative total | 3.40A | 81.6W |
This 3.40A example is below the conservative 4.0A boundary, leaving 0.60A before dynamic, thermal, tolerance, and future-load checks. It is not a universal sizing allowance. Replace every row with the selected equipment’s maximum data and confirm whether the controller can command simultaneous loads during startup, heating, cooling, defrost, alarm, or recovery.
Check how the controller drives the TEC
A Peltier module is a current-sensitive load. Some controllers apply filtered DC, while others use PWM or a bidirectional bridge to switch between heating and cooling. The upstream supply sees the controller’s input behavior, not merely the average thermal output.
Confirm maximum input current, switching frequency, input capacitance, startup surge, regenerative behavior, and any requirement for a supply that can absorb returned energy. Do not assume that a standard AC/DC supply can sink reverse energy. If the controller can regenerate or reverse current, follow the controller manufacturer’s recommended input network and protection strategy.
Measure the 24V bus during the largest step command. Watch for undervoltage, controller reset, oscillation, or excessive ripple. A stable average current does not prove compatibility with a pulsed or bidirectional power stage.
Machine-vision condensation control is one application
This illustrative service-preparation scene shows the source-controlled MDR-100-24 visibly mounted on a 35 mm DIN rail at an open machine-vision station. The supply is unpowered and unwired, its DC OK indicator is dark, and the scene supports fit, access, and application-context discussion only; it is not evidence of an energized installation, a completed customer installation, or a thermal or electrical test result. The documented 55 × 90 × 100mm body and the visible rail and backplate fasteners provide scale.
For this kind of system, the design objective may be to keep an optical window above the dew point, stabilize camera temperature, or qualify equipment through humidity transitions. The thermal load changes with air temperature, humidity, airflow, enclosure sealing, and heat conducted through the mounting structure. Size the TEC, heat sink, fan, and supply as one thermal-electric system.
If the hot side cannot reject heat, the controller may demand more current while the temperature difference gets worse. A higher-current supply cannot correct an undersized heat sink or blocked airflow. Confirm thermal resistance, fan performance, condensation drainage, sensor placement, and control limits before increasing electrical capacity.
Optical qualification is a different duty profile
The second illustrative scene is materially different: the source-controlled MDR-100-24 is visibly staged on an open 35 mm DIN-rail service fixture at an optical qualification bench with an optical breadboard, lens hardware, and calibration target. The supply is unpowered and unwired and its DC OK indicator is dark. This is a service-preparation illustration for mechanical and application context, not a record of an operating qualification test, measured performance, or a completed customer installation; the documented 55 × 90 × 100mm body, rail, breadboard, and mounting bolts provide scale.
An optical qualification rig may emphasize temperature stability, low noise, long dwell time, and repeatability instead of short production cycles. Review supply ripple and noise, controller filtering, grounding, sensor wiring, and electromagnetic compatibility at the system level. A model that passes a steady current calculation can still be unsuitable if switching noise interferes with detectors or measurement electronics.
Apply thermal derating inside the real enclosure
The MDR-100-24 uses a compact plastic DIN-rail enclosure with substantial molded ventilation ribs. Its product envelope is not the required installation clearance. Allow space for free-air movement, conductor bends, terminal access, rail release, and adjacent heat sources.
Measure or estimate the air temperature at the supply after the TEC system and neighboring equipment reach their worst credible duty. A small sealed panel can be much hotter than the room. Apply the derating curve and installation instructions for the exact ordered revision. If the derated capacity is below the verified load or leaves insufficient transient margin, change the architecture or select a suitable higher-capacity model rather than assuming the nameplate current remains available.
Calculate voltage drop and branch protection
TEC controllers can be sensitive to input voltage. Calculate voltage drop across both outgoing and return conductors, terminal blocks, connectors, switches, and protection devices at the highest credible current. Measure voltage at the controller during the demanding thermal state, not only at the supply terminals.
Coordinate branch protection with conductor ampacity, load behavior, available fault current, and required system response. Keep the DC OK contact electrically separate from the load output and use it only within its documented contact rating. Review earthing, bonding, polarity, inductive-load suppression, and the consequences of a fan or pump branch fault.
The deterministic reference deliberately displays both rating sources. It is not permission to use 4.16A or 4.2A on every unit. The exact ordered label, approved specification, ambient conditions, and test results must establish the release limit.
Commission the combined thermal and electrical system
Exercise the actual control sequence through cold start, maximum cooling, maximum heating if applicable, setpoint transitions, fan or pump startup, alarm, and recovery after input interruption. Record supply input condition, 24V voltage at the supply and controller, steady and peak current, enclosure temperature, heat-sink temperature, controlled-object temperature, and recovery time.
Test the worst credible ambient and thermal load, not only a room-temperature bench condition. For systems exposed to condensation, verify drainage, insulation, sealing, and dew-point controls. For precision instruments, record temperature stability and electrical noise during the full dwell period.
The procurement package should identify the exact MDR-100-24 revision, controller and TEC module, load-state matrix, cable lengths and conductor sizes, panel temperature, mounting orientation, branch protection, DC OK use, and acceptance test. This evidence makes the selection reproducible.
Key Takeaways
- The exact MDR-100-24 photo label shows 24V/4A, while the family sheet lists 24V/4.16A and the image caption says 4.2A.
- Use a conservative 4.0A boundary until the ordered revision is confirmed; never merge conflicting source values.
- A 24V TEC power supply must be checked against controller topology, pulsed or bidirectional behavior, transient current, and possible regenerated energy.
- The 55 × 90 × 100mm figure is the enclosure size, not the complete rail, wiring, airflow, and service envelope.
- Machine-vision condensation control and optical qualification have different duty profiles, so their load and noise requirements must be evaluated separately.
- Final approval requires combined thermal and electrical commissioning at the worst credible operating condition.
نتیجه گیری
The MDR-100-24 can be a practical 24V TEC power supply for an industrial thermal-control panel when the verified load remains within the conservatively reconciled rating and the controller, thermal path, wiring, derating, protection, and test results all agree. The small difference among the label, family sheet, and marketing caption is exactly why source discipline matters: confirm the ordered revision, design to evidence, and release the complete system only after measurement.
Frequently Asked Questions
Why does this article use a 4.0A MDR-100-24 limit?
The exact product label shows 24V/4A, while the current family sheet lists 4.16A and the source-image caption says 4.2A. The article uses the lowest clear value until the exact ordered revision is confirmed.
Can the MDR-100-24 directly control a Peltier module?
The power supply provides DC power; a suitable TEC controller or power stage regulates current and direction. Confirm that controller’s input, transient, PWM, and regenerative behavior.
What are the documented MDR-100 dimensions?
The current family sheet gives 55 × 90 × 100mm. Add space for DIN-rail engagement, conductor bends, terminal access, ventilation, and service removal.
What is the DC OK contact used for?
It provides a status dry contact, documented at a maximum 30VDC/1A. It is not a load output and must remain within its interface rating.
Does an 81.6W worked load prove the supply is suitable?
No. It only passes a first arithmetic screen. Controller transients, ambient derating, voltage drop, tolerances, fault behavior, and thermal testing still govern approval.
Can a larger supply solve poor TEC cooling performance?
Not by itself. An undersized heat sink, blocked airflow, poor insulation, or incorrect sensor placement can limit performance even when electrical capacity is available.
