P.T.O.
instabus
®
Technical Manual
Decentralized Power Supply
JB 125C23, 80mA
5WG1125-4CB23
April 2020 / Page 1
USA
Product and Application Description
The decentralized power supply unit JB 125/23 provides the
system power necessary for the
instabus
KNX. The device is
installed in a 4 x 4 inch junction box. The bus is connected
via a bus terminal block.
The integrated choke prevents the data telegrams from
short-circuiting on the bus line.
For each bus line, at least one decentralized power supply
unit JB 125/23 is needed. A second unit is not required un-
less the supply voltage at a bus device is less than 21 V. Up
to eight decentralized power supply units JB 125/23 may be
attached in parallel to a single bus line.
Note: If two or more power supply units are operated in par-
allel on one bus line and if the overload LED is lit on one or
several power supplies, then the bus configuration has to be
changed until the overload display disappears on all units.
A minimum cable length is not required between the decen-
tralized power supplies JB 125/23. Operation of a power
supply unit N125/x2 in parallel to the decentralized power
supplies is permitted on the same bus line as long as the
sum of all short circuit currents of all power supplies does
not exceed 3A.
When several bus devices are installed in short bus cable
distance (e.g. 10 m), e.g. in distribution boards, or in a room
control box AP 641, the power supply units shall be ar-
ranged near these bus devices. The distance along the bus
wire between any bus device and the closest power supply
unit must not exceed 350 m.
If only the decentralized power
supply JB 125/23 is used, then the maximum KNX cable
length in a bus line is 350m for one, 700m for two, and
1000m for 3 or more decentralized power supplies
JB 125/23.
The decentralized power supply unit JB 125/23 has a volt-
age and current regulation and is therefore short-circuit
proof. Short power failures can be bridged with a backup in-
terval of at least 100 ms.
To ensure an uninterrupted power supply a separate circuit
with safety separation should be used for the mains power
supply circuit of all power supply units.
The decentralized power supply units JB 125C23 are pow-
ered by AC 120V.
Application Program
No application program required
Technical Specifications
Input voltage
• rated voltage: AC 120V, 50...60Hz
Rated power consumption
approx. 10 W
Output voltage
• rated voltage: DC 29 V (class 2)
• safety extra low voltage (SELV)
• permissible range: DC 28 ... 30 V
Output current
• rated current 80 mA
• short-circuit current: limited to 0.2 A
Backup interval
on input voltage failure:
≥ 100 ms at rated current
Display elements
• 1 red LED: for indicating
- a shorted-out bus line or device over-load
Connections
•
Bus line : Bus connection pins for connection of the
screwless bus terminal block (red-
black) 0.6…0.8
mm Ø
single core, strip insulation 5mm
•
mains power:
see Location and Function of Interface Elements
Physical specifications
•
housing: plastic
•
dimensions (L x W x D):
length : 70 mm (2.76 inch)
width: 90 mm (3.54 inch)
depth: 44.6 mm (1.76 inch)
•
weight: approx. 171 g
•
fire load: approx. 5 MJ
•
Installation: in a junction box (min. dimensions (L-W-D))
Length: 4 inch (101.6 mm)
Width: 4 inch (101.6 mm)
Depth: 2 inch (50.8 mm)
Electrical
safety
•
Degree of pollution (according to IEC 60664-1): 2
•
Type of protection (according to EN 60529): IP 20
•
Overvoltage category (according to IEC 60664-1): III
•
Bus: safety extra low voltage SELV DC 24 V
•
Device complies with: EN 50428
Electromagnetic compatibility
complies with EN 50428
Environmental specifications
•
Ambient operating temperature:
-
5 … + 45 °C (+ 23 ... + 113
F)
•
Storage temperature:
-
25 … + 70 °C
(- 13 ... + 158
F)
•
Relative humidity (not condensing): 5 %
…
93 %
Reliability
•
Failure rate: 109 fit at 40°C
Markings
EIB, KNX, UL
Listings and Certifications
CE mark
complies with the EMC regulations (residential and func-
tional buildings) and low voltage regulations
UL listed (E464611)
UL 916, Open Energy Management Equipment
