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LED Display Power Supply Installation Notes and Parallel Use Instructions

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LED Display Power Supply Installation Notes and Parallel Use Instructions

1. LED Display Power Supply Installation Notes

Almost all the LED display power supplies of HWAWAN power are cooling by conduction. Generically LED power supply can’t cool enough to meet the requirement by itself. So it’s necessary to add a heat sink to help with dissipation. The heat sink could be a cabinet (metal) or a dedicated radiator. In order to meet the requirement of de-rating curve and performance ①, following items should be considered for installation:
1. The button side of PSU should be fixed on the radiator (cabinet) by screws to achieve a good cooling effect for the button side is where the heat most concentrated. The surface of the radiator should be as smooth as possible.
2. The size of an Al radiator should be chose according to the output condition of the PSU as below:
1) The size of radiator should be no less than 300m*300m*3mm (L*W*H) for PSU with an output voltage of 3.8-5.0V, and a output current of 25A, 30A, 40A;
2) The size of radiator should be no less than 400mm*400mm*3mm (L*W*H) for PSU with an output voltage of 3.8-5.0V, and a output current of 45A, 50A,60A;
3) The size of radiator should be no less than 450mm*450mm*3mm (L*W*H) for PSu with an output voltage of 3.8-5.0V, and a output current of 80A.
3. The contact between a PSU and a radiator is easily become point contact rather than surface contact due to their large contact area and metal-structure, In order to increase the actual contact area, one of the following items should be considered for installation:
1) Silicone grease should be painted between the contact side ( Thermal conductivity >2.0w /m. k are recommended).
2) Put a Silicone thermal pad to take place of silicone grease ( Thermal conductivity >2.0w /m. k are recommended). For thickness, the thinner, the better for cooling effect in theory. 0. 5mm is recommended for considering of tenacity.
(Note: ①: The performance shown in the Specification For Approval is tested under the recommended condition, see the Specification For Approval for details.)

Appendix 1 Characteristics of silicone thermal pad and thermal silicone grease:

1.Thermal Silicone Pads
● Thermal silicone pads offer a certain level of flexibility, excellent insulation, compressibility, and natural adhesion on the surface.
● Thermal conductivity: 1.5 ~ 3

2.Thermal Grease
● Excellent electrical insulation, thermal conductivity, low oil separation (tending to zero), resistance to high and low temperatures, water, ozone, and weather aging. It remains in a paste-like state for long-term use at temperatures ranging from -50°C to +230°C without solidifying.
● Thermal conductivity: 0.8 ~ 5.0

Characteristics of silicone thermal pad and thermal silicone grease

Appendix 2 Table of thermal conductivity of common materials:

Table of thermal conductivity of common materials

2. LED Display Power Supply Parallel Use Instructions

    In some specific application occasions, such as live broadcasting hall, high end meeting room, largeperformance stage, etc., the reliability requirements of LED display screen are relatively high, and the power supply solutions should be adjusted accordingly. So the power supply solutions with current-sharing function should be considered. The connection examples are shown in figure l, figure 2 and figure 3. During normal operation, the total output current is evenly distributed by each power supply unit. let’s assume the total current with I and the number of paralleled power supply with n, then the current of each PSU is I/n.
When one power supply is abnormal, the output current of the rest power supplies increases, and the output current of each PSU is I/ (n-1). We need to make sure that the rated output current of each PSU larger than I/ (n-1) during the design. In this way,  The display screen will not be affected when one of the paralleled power supplies operates abnormal, which greatly providing equipment reliability. Thanks to the lower power consumption for each PSU, the life of the power supply and surrounding components will be longer at the same time.
    We provide LED power supply with both versions, there are current-sharing version and non- current sharing version. Here are some tips for current-sharing version.
    The maximum total output current should follow the following equation: maximum total output current = rated current of each PSU/ (1+ degree of current-sharing imbalance)*100%* number of paralleled PSU.
    The P.G signal indicates the working condition of the PSU. The high level indicates the normal operation, while the low level indicates the abnormal operation. Generally, the high voltage of p.G signal is 2. 8V, while the low level is 0v. Please refer to the definition of Specification For Approval for details. You can monitor the operation of a PSU by detecting the P. G signal.
Notes:
1. Power supply without backup function shall not be used in parallel;
2. It is recommended that the number of paralleled power supplies with current sharing function shouldnot exceed.

Fig.1 Backup connection for power supplies with single output

Fig.1 Backup connectlan for power supplles with sinsle output

Fig.2 Backup connection for power supplies with dual outputs (+Vl supports backup, +V2 does not support backup)

Fig.2-Backup-connection-for-power-supplies-with-dual-outputs

Fig.3 Backup connection for power supplies with dual outputs (+V1 support backup, +V2 supports backup)

Fig.3-Baekup-conneetion-for-power-supplies-with-dual-outputa
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