Omni8/16C/Omni8P User Manual
UMC1480R24.pdf
43
© Omniflex 2021
Reverse Polarity Protection
The Model C1421 AC option will operate with a dc supply connected in either polarity, but the above
connections are required to comply with radiated emission standards.
The Model C1422 DC option is reverse polarity protected. Reversing the dc supply will not damage the
unit, but it will not function.
4.9.3
Omni16C Intrinsically Safe Version (Ex ic)
The Omni16C Ex is fitted with special DC power supply unit. The maximum supply voltage for this unit
is Um=27 VDC. Connection of voltages higher than 27VDC is not allowed.
Note: Connection of a reverse polarised power supply to the unit will blow an internal fuse with no auto
recovery. This fuse can only be replaced by an Omniflex service centre
Connect the supply to the supply terminals P-1, P-2 and P-3.
Table 4-5 – Power Supply Terminals
DC Connection
27VDC maximum
Terminal
Connection
P - 1
+
P - 2
-
P - 3
Safety Earth
4.9.4
24Vdc Power externally available (non Ex versions only)
With either internal power supply option installed, the 24Volt terminals C-1 and C-2 now become a
limited source of 24Volt power for use with other devices. For example, a 24 volt dc audible device
could be powered by the Omni8/16Cfrom these terminals.
Calculate the externally available current from this 24Vdc supply as follows:
1.
The maximum current capacity from the optional internal power supply is 2.2Amps at 24Vdc
2.
Determine the maximum internal consumption of the Omni8/16C (see Section 4.8)
3.
The difference between this and 2.2 Amps is the available current.
Example:
A 24-point panel mounted alarm system is required, made up of a backlit LED Omni16C (Model C1480)
and a backlit LED Omni8C (Model C1490).
Design considerations:
1.
What is the total power requirement of the system?
2.
Can an optional C1421 internal ac power supply fitted in the Omni16C power the Omni8C as
well?
