QT20.361

Q-Series

Oct. 2006 / Rev. 1.0 DS-QT20.361-EN

All parameters are specified at 36V, 13.3A, 3x400Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

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Germany

Power supplies can be paralleled to increase the output power.

Fig. 27-10 Schematic for parallel operation

Instructions for parallel use:

Unit B

-

+

Load

+

-

AC

DC

AC

DC

-

+

Unit A

a)

Use only power supplies from the same series (Q-Series).

b)

Adjust the output voltages of all power supplies to

approximately the same value (±500mV).

Otherwise, the DC-ok signal might not work properly.

c)

A fuse (or diode) on the output is only required if more

than three units are connected in parallel.

d)

Keep an installation clearance of 15mm (left / right)

between two power supplies and avoid installing the

power supplies on top of each other.

Power supplies can be paralleled for redundancy to gain a higher system availability. Redundant systems require a

certain amount of extra power to support the load in case one power supply unit fails. The simplest way is to put two

Q-Series power supplies in parallel. This is called a 1+1 redundancy. In case one power supply unit fails, the other one

is automatically able to support the load current without any interruption. Redundant systems for a higher power

demand are usually built in a N+1 method. E.g. Five power supplies, each rated for 10A are paralleled to build a 40A

redundant system.

Please note: This simple way to build a redundant system does not cover failures such as an internal short circuit in

the secondary side of the power supply. In such a - virtually nearly impossible - case, the defect unit becomes a load

for the other power supplies and the output voltage can not be maintained any more. This can only be avoided by

utilizing decoupling diodes which are included in the decoupling module YR2.DIODE. (One module per power supply)

Recommendations for building redundant power systems:

a)

Use separate input fuses for each power supply.

b)

Monitor the individual power supply units. A DC-ok lamp and a DC-ok contact is already included in the units

This feature reports a faulty unit.

c)

When possible, connect each power supply to different phases or circuits.

d)

It is desirable to set the output voltages of all power supplies to the same value to avoid a false DC-ok signal.

Daisy chaining (jumping from one power supply output to the next) is allowed as long as the maximum current

through one terminal pin does not exceed 25A. If the current is higher, use a separate distribution terminal block.

Fig. 27-11 Daisy chaining of outputs

Fig. 27-12 Using distribution terminals

Power

Supply

+ +

- -

Input

Power

Supply

+ +

- -

Input

Load

+

-

max 25A!

Power

Supply

+ +

- -

Input

Power

Supply

+ +

- -

Input

Load

+

-

Distribution

Terminals

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