Honeywell SN0500 - Manual (Page 4)

GAS LEAK DETECTOR INSTALLATION & USER GUIDE
3. POWER SUPPLY
The Power supply is connected at Con 1 (see Fig. 1)
Green LED on - shows power connected.
Pin 1 = 0V,
Pin 2 = 12 to 24 VAC or 12 to 30VDC,
Pin 3 = Earth.
The 0V (pin 1) on the power supply terminal block (CON 1) can withstand 50V
AC or DC with respect to the 0V (Pin 1) on the output terminal block (CON 3). If
this is likely to be exceeded use an isolated power supply.
On the power supply side 12V is the minimum voltage at the terminals. Power
consumption is 4W max. It can draw 0.33Amp at 12V, so voltage drop along the
supply cable should be considered when selecting supply cable, type and length. For
example, for cable resistance 10ohm/100m allowing for the flow and return total cable
resistance for 100m is 20ohm and voltage drop along the cable is 6.6V. Minimum DC
supply then should be 19V.
If you need to use a cable of greater diameter that 1.5 mm sq, you can use a terminal
block at each sensor position capable of taking the larger cable and connect from that
into the CON1 terminal block using 1mm sq wire. Alternatively use local power
supplies to reduce cable runs and voltage loss.
4. ANALOGUE OUTPUTS
Analogue Outputs which indicate the concentration of gas refrigerant in the air, are at
Con 3 (see Figure 1.)
A two-core communication cable should be used to connect the outputs to a
monitoring and control system; a screen is not required.
Pin 1 = 0V
Pin 2 = 4-20mA. Load resistance must be less than 400Ω
Pin 3 = 0-10V. Load resistance must be greater than 100Ω
Pin 4 = 0-5 V. Load resistance must be greater than 10KΩ
When connecting the 4-20mA to the control panel, we suggest using Belden 8761,
22awg single pair shielded or alternatively an alarm type cable of 7/0.2mm, 22awg.
EN1B-0014UK07 R0404 4