Calculations B
Shield Fire, Safety and Security Ltd.
Shield A-XT Releasing Fire Control Panel - Installation and Operation Manual SEXTCP-OM
Revision E01.00
85 of 127
2 Calculate the minimum operating-voltage (VSRV
min
) of the Solenoid Release Valve (SRV) when it is 65% of
the nominal rating.
where,
Vop
min
= VSRV
nominal
X %Vout
= 24 VDC x 0.65
3 Calculate the voltage-drop of the circuit (V
drop
) when the EXTING. output is at the minimum level (Vout
min
) and
when the operating-voltage of the SRV is at the minimum level (VSRV
min
).
where,
Vdrop = Vout
min
- Vop
min
- V
EOLD
= 20.4 VDC - 15.6 VDC - .07 VDC
4 Calculate the maximum current of the circuit (I
max
) when the SRV operates 65% below its nominal
operating-voltage and power across the SRV is maximum.
where,
Imax = WSRVmax / Vop
min
Refer to the manufacturer specifications of the SRV for the maximum power rating (WSRV
max
).
= 9.11 W / 15.6 VDC
Vop
min
= 15.6 VDC
Vdrop = 4.1 VDC
Imax =
584 mA
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