CS10.481

C–Series

Nov. 2006 / Rev.1.1 DS-CS10.481-EN

All parameters are specified at 48V, 5A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

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Loads such as decelerating motors and inductors can feed voltage back to the power supply. This feature is also called

return voltage immunity or resistance against Back- E.M.F. (Electro Magnetic Force).

This power supply is resistant and does not show malfunctioning when a load feeds back voltage to the power

supply. It does not matter, whether the power supply is on or off.

The maximum allowed feed back voltage is 63Vdc. The absorbing energy can be calculated according to the built-in

large sized output capacitor which is specified in chapter 8.

Standard miniature circuit breakers (MCBs) can be used for branch protection. Ensure that the MCB is rated for DC

voltage, too. The following tests show which circuit breakers the power supply typically trips.

Circuit breakers have huge tolerances in their tripping behavior. Therefore, these typical tests can only be used as a

recommendation or for comparing two different power supplies. Furthermore, the loop impedance has a major

influence on whether a breaker trips or not. Two tests were performed, representing typical situations:

Test 1: Short circuit with S1 on the power supply end of the cable (loop impedance approx. 20mOhm)

Fig. 25-3 Branch protectors, test circuit 1

Circuit

Breaker

Power

Supply

AC

DC

+

-

I

Load

+

-

S1

Parameters:

Input voltage:

230Vac, load current:

0A

The following circuit breaker tripped during the test:

A- or Z- Characteristic::

equal or smaller 25A

B- Characteristic:

equal or smaller 16A

C- Characteristic:

equal or smaller 10A

Test 2: Short circuit with S1 on the load end (additional impedance included; represents longer load wire length).

Fig. 25-4 Branch protectors, test circuit 2

R

Circuit

Breaker

Power

Supply

AC

DC

+

-

I

S1

Load

+

-

Parameters:

Input voltage:

230Vac, load current:

0A

The following circuit breaker tripped during the test:

A- or Z- Characteristic::

≤ 16A and R= 82mOhm

B- Characteristic:

≤ 6A and R= 180mOhm

C- Characteristic:

≤ 6A and R= 180mOhm

What does this resistance mean in wire length?

0.5mm

2

0.7mm

2

1.0mm

2

1.5mm

2

2.5mm

2

4.0mm

2

82mOhm

2.3m

3.2m

4.6m

6.9m

11.4m

18.3m

180mOhm

5.0m

7.0m

10.0m

15.0m

25.1m

40.1m

Example:

Which wire gauge must be used to trip a B-Characteristic circuit breaker with a rating of 6A? The load wire length is

21m.

Answer: A 6A B-Characteristic circuit breaker requires a loop impedance of less than 180mOhm (test results). The wire

length table shows that up to 25.1m wire with a cross section of 2.5mm

than 2.5mm