PULS QS40.241 Power Supply Practical Guide

Attention: When the number of parallel units exceeds 3, each output needs to be equipped with a 50A or 63A fuse or circuit breaker.

5.2 Redundant Configuration (Improving System Availability)

1+1 redundancy: Two power supplies are connected in parallel, each with 50% load. After one fails, the other bears 100% of the load. For a 40A system, usually two QS40.241s each have 20A, and in the event of a fault, a single unit can output 40A (still within the rated range).

More reliable redundancy solution: Use YR80.242 or YR40.245 redundant modules, with MOSFET decoupling internally, to avoid dragging down the entire bus when one power supply is short circuited internally. Redundant modules also support hot swapping.

Suggestion:

Each power supply uses independent input fuses or independent branches.

Set to 'Parallel Use' mode.

Use the DC-OK relay contacts of each power source for status monitoring.

5.3 Series connection to obtain higher voltage

QS40.241 can be connected in series up to a total output voltage of no more than 150Vdc. Attention: Exceeding 60Vdc no longer belongs to SELV, and an anti electric shock protection cover must be installed, and the output must be grounded. When connecting in series, a gap of 15mm should also be maintained on both sides.

Pulse load calculation: reasonable utilization of BonusPower

Many loads, such as wireless data radios, motor starters, and solenoid valves, have high pulse current characteristics. QS40.241 allows a maximum pulse power of 150% of the rated power (i.e. 1440W). But the following conditions must be met simultaneously, otherwise HiccupPLUS will be triggered:

Pulse power ≤ 1440W.

Pulse duration ≤ allowable BonusPower time (refer to Figure 6-5 in the data manual, which decreases with increasing power).

RMS output current ≤ 40A.

Duty cycle ≤ 0.75.

Actual case: A certain device continuously consumes 480W (50% load) and requires a 1440W pulse every 10 seconds, lasting for 1 second.

From the "Maximum Duty Cycle Curve" graph (Fig.26-2), when Ppeak=150% and P0=50%, the maximum duty cycle is approximately 0.37.

Required duty cycle=1 second/10 seconds=0.1<0.37, therefore feasible.

If the pulse lasts for 3 seconds and the duty cycle is 3/10=0.3, it is still within the range, but the recovery time needs to be checked.

Calculate the necessary pause time: T0=Tpeak × (1/duty cycle -1). When the duty cycle is 0.37, T0=1 × (1/0.37-1) ≈ 1.7 seconds, and there should be margin in the actual design.

Engineers can quickly evaluate using the reference values provided in the table, such as a pulse width of approximately 2.7 seconds at a load of 1440W and a duty cycle of 10%.

Selection and matching of output circuit breakers (MCBs)

In order to quickly cut off the fault in the event of a branch short circuit without affecting other circuits under the same power supply, the downstream MCB must achieve magnetic tripping (usually within 10ms). This requires the power supply to provide a sufficiently large peak current and a sufficiently low line impedance.

QS40.241 can provide a peak value of 110A/10ms, which is sufficient to drive most C-type or B-type miniature circuit breakers. However, limited by the length and cross-sectional area of the wire, the maximum wire length that can guarantee magnetic disengagement is as follows (for example):

Wire diameter C-6A MCB B-10A MCB

1.5mm² 21m 24m

2.5mm² 34m 40m

(The complete table can be found in Table 26-5 of the original text). Attention: The length of the wire needs to be calculated based on the total length of the positive and negative wires (round-trip distance).

If the actual line length on site exceeds the table value, it is necessary to:

Increase the wire diameter.

Use MCB with lower rated current instead.

Install local fuses or electronic fuses at the load end.

Internal data recording: the 'black box' for fault analysis

QS40.241 has a built-in microcontroller that continuously records the following data, which can be read through the PULS service tool even if the device is damaged:

Total operating hours.

The proportion of consumed lifespan (based on temperature and time).

Up to 47 maximum environmental temperature events (with timestamps).

Up to 47 maximum input voltage events.

Input the number and timestamp of overvoltage transients.

The number and timestamp of over temperature shutdown.

Number of power on cycles.

Internal error report.

This is very valuable for analyzing occasional faults on site, such as high-temperature shutdown and input surge damage.

Battery Charging Application

QS40.241 can charge two 12V lead-acid batteries (24V system) connected in series. Please note:

Accurately set the output voltage (no-load, battery terminal measurement) to float charge voltage, for example, 27.5V at 25 ℃, with an increase/decrease of approximately 0.3V every 10 ℃.

Connect a 50A or 63A circuit breaker or isolation diode in series between the power source and battery to prevent reverse discharge.

When the power is turned off, the reverse leakage current is typically 35mA, which may deplete the battery for a long time. It is recommended to use diode isolation.

Common troubleshooting guide