Enviro EA800 owner manual Humidity Sensors, 4-20mASensors, Theory of Operation

General Information

Humidity Sensors

Table 6 lists the humidity sensors available for use with the EA800 Alarm System.

Table 6	EA800 Compatible Humidity Sensors
Sensor		Part Number	Description	Operating Range/Parameters
HA-III+		PN M-001-0091	Humidity monitoring module	5% to 95% rh
				(non-condensing)
Wireless		PN M-001-0126	Wireless humidity monitoring	5% to 95% rh
Humidity			module	(non-condensing)

4-20mA Sensors

Theory of Operation

Industry standard 4-20mA sensors can be used with the EA800. However, it is important to verify that this type of sensor will operate properly over the entire output range.

Figure 6 shows an example of the loop circuit for a 4-20mA sensor whose minimum operating voltage is 8V or less when connected to an EA800 base unit that is powered with 12VDC.

If Vsensor = 8V and Aux Power = 12V

4-20mA Transmitter

+

Vsensor

-

J5

+

DC + Aux Power

(-)

200O

+

(-)

Input N

J6

EA800

-

Max Load of

200O includes

1000' of 22 AWG

4.0V (2 conductor) wire connecting the EA800 to the 4-20mA sensor

+

Figure 6 I4-20mA Sensor Wiring Diagram - EA800 Aux Power Supply

Figure 7 shows an example of the loop circuit for a 4-20mA sensor whose minimum operating voltage is greater than 8V when connected to an EA800 base unit that is powered with 12VDC.

If Vsensor > 8V and Aux Power = 12V		J5			EA800
		+
4-20mA	External	DC
	Supply	+	Aux Power
Transmitter
+		(-)		-
Vsensor					Max Load of
					200O includes
-			200O	4.0V	1000' of 22 AWG
		+			(2 conductor)
					wire connecting
					the EA800 to the
					4-20mA sensor
		(-)		+
		Input N
		J6

Figure 7 4-20mA Sensor Wiring Diagram - External Power Supply

D-011-0152 11