CS5.241, CS5.241-C1, CS5.241-S1

C–Series

Dec. 2006 / Rev. 1.3 DS-CS5.241-EN

All parameters are specified at 24V, 5A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

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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 8A

B- Characteristic:

no tripping

≥ 6A

no breaker available < 6A

C- Characteristic:

equal or smaller 4A

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::

≤ 6A and R= 180mOhm

B- Characteristic:

no tripping

≥ 6A

no breaker available < 6A

C- Characteristic:

≤ 3A and R= 270mOhm

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

180mOhm

5.0m

7.0m

10m

15m

25m

40m

270mOhm

7.5m

10.5m

15m

23m

38m

60m

Example:

Which wire gauge must be used to trip a C-Characteristic circuit breaker with a rating of 3A? The load wire length is

21m.

Answer: A 3A C-Characteristic circuit breaker requires a loop impedance of less than 270mOhm (test results). The wire

length table shows that up to 23m wire with a cross section of 1.5mm

1.5mm

The unit is designed to supply any kind of load, including unlimited capacitive and inductive loads.