Issues with power supply redundancy design

When designing for redundancy, the key goal is to ensure that the system can continue to operate without interruption in the event of a power failure. A basic power supply redundancy design typically includes at least two independent power supply modules, which can be configured in one of the following ways: 1. Parallel redundancy (N+1 redundancy): In this configuration, two or more power supplies operate in parallel. Usually, an additional power supply (N) is added to the required number of power supplies (+1) to ensure that there is a backup supply available to take on the load if necessary. If one power supply fails, the other ones will immediately take over the load, ensuring that the instruments continue to function properly. 2. Hot backup redundancy: In this design, one power supply serves as the main power source to provide electricity, while the other operates in standby mode. If the main power supply fails, the backup power supply will automatically start up and take over power supply. 3. Failover switching: This method involves the use of automatic switching devices or manual switching devices. When there is a problem with the main power supply, the system automatically or manually switches to the backup power supply to maintain continuous power supply. Regarding the redundant design you mentioned, here are some potential issues and their corresponding solutions: – Is there proper isolation between the power supplies? It is important to ensure isolation between power modules to prevent feedback or damage. - Can power supply failures be detected correctly? The design should include a mechanism for monitoring the power supply status, so that it can switch to a backup power source promptly in the event of a failure. - Is the switching mechanism safe and reliable? Ensure that automatic or manual switching can occur seamlessly in the event of a failure, without causing any brief power interruption to the instruments. - Is the load distribution reasonable? For power supplies operating in parallel, it is necessary to consider whether there is load-sharing control to ensure balanced loading among the power supplies. If there are issues with the design, it may be necessary to improve the connection methods between power modules, as well as the fault detection mechanisms, switching mechanisms, and load balancing controls. Possible modification methods include adding isolation diodes, using reliable failover switches, and optimizing the load-sharing circuitry. .

Firstly, connecting two 24V power supplies in parallel directly is a problem, as the voltages of the two 24V sources cannot be exactly equal, which will result in backflow. It must be isolated with a diode. The principle is as shown in the figure. It is recommended to purchase ready-made redundant power supply modules, which not only provide isolation between circuits A and B but also include alarms for circuits A and B. The Phoenix brand is good for industrial use, and its price is relatively high.

The design is unreasonable. An air switch should be installed at each 220V AC input, and a diode should be installed at each 24V DC output.

1. 220VAC with circuit breaker from the PDP cabinet to the auxiliary cabinet； 2. A DC circuit breaker is installed on the 24VDC output; some manufacturers also use terminals ； 3. A redundant 24V power supply is required; redundant modules can be used to achieve power supply redundancy ； 4. Select redundant modules such as 20A or 40A based on the power capacity of the power supply ； 5. Generally, for a 40A power supply, 2 redundant 40A modules are used; one power supply is connected to one redundant module ； 6. The 24VDC output wires should not be connected to the power terminals; the outputs of redundant modules can be connected to the busbars separately ； 7. There are also power supplies that do not come with redundant modules; these can be connected in parallel using MOSFET transistors ； 8. Fault alarms from the 24VDC power supply are sent to the control system for alerting.

Floor 5 explained it very clearly, though it was a bit messy: lol

For DCS, add a voter. For SIS, use two voters. The power supply module has its own alarm channel; the alarms are connected together. Finally, it is aggregated into the DI card.

This power supply is redundant. However, it is necessary to check whether the model meets the design requirements for preventing reverse breakdown; if so, there is no need to install a reverse diode in parallel.

1. A circuit breaker of appropriate capacity should be installed for 220VAC separately. 2. A high-power diode is added to each 24VDC output terminal; in the event that one voltage regulator fails, the other can continue to function, providing redundancy.