22
INM4500-2
Mar 2009
6.2 Digital Output modules
The single channel Digital Output (DO) module range enables on/off devices in a hazardous area to be
controlled from the safe area. Some units are loop powered while others enable solid-state switching by
providing independent power supplies.
6.2.1 MTL4521 - Solenoid Alarm driver
Loop powered, IIC
The MTL4521 is a loop-powered module that enables a device located in the hazardous area
(IIC gas group) to be controlled from the safe area. The MTL4521 can drive up to 48mA into a
certifi ed intrinsically safe low-power load, as well as non-energy-storing simple apparatus such as
an LED.
Note
: Signal plug HAZ1-3 is required for access to the earth leakage detector function.
Figure 6.9
LED indicators
for MTL4521
STS
MTL4521
Hazardous area
Safe area
1 2 3 4 5 6
7 8 9 10 1112
13 14
Vs
Vs+
2035V dc
+
Solenoid,
alarm or
other IS device
To MTL earth leakage detector
Terminal
Function
1
Output
–ve
2
Output
+ve
3
To earth leakage detector
10
Supply
+ve
11
Supply
–ve
