Current sharing decides how parallel supplies divide a load. ORing limits unwanted reverse-current paths between sources. Redundancy asks whether the system can continue after a failure. These are related design decisions, but none automatically proves the other two. Specify the required functions separately before joining DC outputs.
Why equal voltage labels do not ensure equal current
Two supplies marked “24 V” can have slightly different actual setpoints, output characteristics and cable drops. When connected to a common bus, the source with the higher effective voltage can take more of the load. Equal wire lengths alone do not correct every difference in regulation or dynamic response.
Start by deciding whether the aim is increased capacity, reduced loading of each unit, uninterrupted operation after a fault, or some combination. A system that needs both sources to meet its normal load has a different failure requirement from one whose remaining source can carry everything after the other is isolated.
Droop sharing uses a voltage-current slope
In a droop-sharing architecture, output voltage intentionally decreases as source current increases. This creates a mechanism for another source to take more current, but the balance depends on the characteristic slopes, setpoints and distribution paths. Active-sharing arrangements instead coordinate compatible supplies through a control mechanism. Analog Devices’ current-sharing explanation distinguishes these approaches and describes designs that combine sharing with controlled diode behaviour.
Consider a simplified, hypothetical example—not a PSP characteristic. Let source A follow V = 24.1 − 0.05 × IA and source B follow V = 24.0 − 0.05 × IB, with volts and amperes as units. At a common bus and a total 10 A load, the equations give IA = 6 A and IB = 4 A. Both reach 23.8 V, yet the currents are not equal.
This example shows why a small setpoint difference matters. The permitted voltage variation at the load and the acceptable sharing imbalance belong in the specification. It is not a recommendation to add arbitrary resistors or deliberately adjust unrelated supplies until they appear to share.
What the PSP-600-24 interface actually tells us
The original PSP-600-24 has two guarded terminal rows. Its matching drawing identifies the upper-row functions as AC/L, AC/N, FG, P for current share, POK, RCG and RC. The lower row provides multiple +V and −V terminals for one DC output, not eight independently regulated channels.
The P connection is relevant evidence of a current-share interface. It is not a complete application instruction. The available sheet does not establish the permitted number of parallel units, share-bus protocol, achievable current balance, required wiring arrangement or whether reverse-current isolation is included. Obtain those details for the supplied revision rather than guessing a connection from the terminal name.
Keep the product evidence consistent too. The original photographed label is +24 V, 25 A, while the public listing and supplied sheet contain differing input, power and dimensional entries. This article therefore does not calculate an approved combined output rating from those records. The order-specific specification must settle the usable rating before a system capacity claim is made.
ORing controls backfeed, not equal contribution
An ORing path uses a diode or an appropriately controlled semiconductor arrangement to restrict reverse current into another source. Depending on the design, one supply can carry most of the load while the other stands ready. That can be valid source selection without being balanced sharing.
Include forward loss, thermal design, reverse blocking behaviour and the intended fault cases. “Ideal diode” describes a controlled function, not a lossless physical component. Hot-swap control is another distinct requirement: controlled insertion into a live bus is not established simply by the presence of ORing. Analog Devices’ ORing and hot-swap discussion explains the separate roles.
Check surviving capacity, not only total installed capacity
For a redundant architecture, define the required load after the specified failure and verify that the remaining available sources can carry it under the actual environment. Two hypothetical 10 A sources supporting a 16 A load may provide useful combined capacity, but one surviving 10 A source cannot sustain that same load. Load shedding or additional capacity would be a separate design decision.
Review common failure paths as well: shared input protection, a common connector, cooling failure or a downstream short can affect more than one source. A complete review considers the bus, isolation devices, distribution and monitoring—not just the number of supplies.
Frequently asked questions
Does an ORing module make two supplies share equally?
Not necessarily. Reverse-current isolation and load balancing are distinct functions. Check whether the particular architecture explicitly supports both.
Can I parallel any two supplies with the same voltage label?
No. Use a manufacturer-supported arrangement with compatible revisions and documented current-sharing, protection and installation requirements.
Does the PSP P terminal prove built-in redundancy?
No. It identifies a current-share function in the matching drawing, not a complete redundant-system approval or proof of internal ORing.
Write an architecture brief for the supplier
Provide normal and transient load, acceptable voltage tolerance, surviving-load requirement after a failure, supply quantity, exact revisions, distribution layout and monitoring needs. Request the approved current-sharing application note and clarify whether additional ORing or hot-swap hardware is required.
Review the WEHO PSP-600 product listing and request a revision-specific architecture review. A useful answer will separate load balance, fault isolation and available capacity instead of describing all three simply as “parallel operation.”
