B&B Electronics NTPS-24-5 - Datasheet - Manual (Page 17)

CS5.241, CS5.241-C1, CS5.241-S1
C–Series
24V, 5A, S INGLE P HASE I NPUT
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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25.4. O
UTPUT
C
IRCUIT
B
REAKERS
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
2 are below 270mOhm. A wire not smaller than
1.5mm 2 shall be used.
25.5. I NDUCTIVE AND C APACITIVE L OADS
The unit is designed to supply any kind of load, including unlimited capacitive and inductive loads.