iSMA-B-FCU Hardware User Manual
www.ismacontrolli.com
DMP242en | 1st Issue rev. 3 | 02/2022
page 23 of 53
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5.2.2 Digital Outputs
All digital outputs are based on relays, which can operate with 230 V AC voltage (in iSMA-
B-FCU-LL, digital outputs are working with 24 V AC). The iSMA-B-FCU device has 2 types of
digital outputs:
O1-03 and 05: relay outputs connected directly to power supply terminal;
O4: a relay separated from iSMA-B-FCU device circuits.
O1-O3 Fan Relays
The iSMA-B-FCU device is equipped with three relay outputs, designed for connecting up
to 3 speed fans. The way the fans are connected (depending on the number of speeds) is
presented in the figure below. The common terminal for those outputs is connected
directly to the power supply
“L”
terminal.
The exemplary fan connection is presented in the figure below.
In case of the iSMA-B-FCU-HL controller, the sum of power consumption of both triac
outputs and 24 V AC output cannot exceed 0,3 A (7 VA):
I
max
=
0,3 A
= I
TO1
+ I
TO2
+ I
24VOut
.
WARNING!
Outputs O1-O3 and output O5 are protected by a built-in 6 A fuse. Total
current for digital relays outputs O1-03 and O5 cannot exceed 6 A.
WARNING!
It is forbidden to use a fuse with current exceeding
6 A!
Higher current
may permanently damage device and cause danger to the user and to the equipment!
WARNING!
In iSMA-B-FCU-LL, the 24 V AC fan motor is required.
