2.2. Direct Parallel

In Direct Parallel, each Accessory operates as a standalone unit on a shared output bus: each unit regulates its output entirely with its own local control loop, driven only by its own set-points and measurements, and is programmed and controlled independently via the front panel, MagnaWEB, or computer programming interface. No MagnaLINK™ cabling or inter-unit communication is required. In direct-parallel operation, the system continues supplying the load even after a unit is removed or goes offline.

2.2.1. Voltage Regulation and Load Sharing

All unit output terminals are bussed; all positives are connected together and all negatives are connected together. The voltage set-points are staggered by a small offset from unit to unit. One unit — the regulating unit — is programmed to the target bus voltage and holds the bus in constant-voltage (CV) regulation. Every other unit is programmed a small increment higher, so each sees the bus below its own voltage set-point and delivers its full programmed current in constant-current (CC) regulation, acting as a current source. The regulating unit supplies the balance of the load and is effectively the last to source current; the units therefore do not share the load equally. The front-panel CV / CC / CP indicators reflect this: the current-source units display CC while delivering their programmed limit, and the regulating unit displays CV.

Stagger the voltage set-points between units by a small offset, approximately 0.2% of the model’s full-scale voltage rating. Program the current and power limits of each unit to its rating, or to the desired ceiling. Because each unit provides its own independently programmable over voltage trip (OVT), over current trip (OCT), and over power trip (OPT) protection, set these thresholds above the expected operating points; under normal load sharing the units regulate to their set-points and do not reach the OVT, OCT, or OPT trip points.

2.2.2. Wiring and Control

Size the bus bars and cabling for the total system current. No turn-on sequencing is required: units may be enabled together and in any order, with each unit enabled by any of the standard methods — the front panel, a computer command, or the External User I/O. To control the system with a common set of hardwired signals, wire the Enable, Interlock, and Clear Fault digital inputs in parallel across all units. For a controlled shutdown, the latching Interlock is preferred over removing the Enable signal.

2.2.3. Redundancy and Scalability

If the regulating unit fails or goes offline, the unit with the next-higher set-point automatically transitions to voltage control and assumes regulation of the bus; in factory testing this transfer is seamless. The remaining units stay enabled and continue delivering current, so the system keeps supplying power, subject to the remaining total capacity. This is the key difference from Master-Slave operation, where the loss of any unit takes the entire system offline. For true redundancy, margin in extra capacity by paralleling an additional unit so the remaining units can carry full load if one drops out.