INM 5500 Rev 10
36
6 .2 .7
MTL5526 - Switch Operated Relay
Two channel, output
The MTL5526 enables two separate IS circuits in a hazardous area to be relay-contact controlled
by two on-off switches or logic signals in a safe area. Applications include the calibration of
strain–gauge bridges; changing the polarity (and thereby the tone) of an IS sounder; the testing
of IS fire alarms; and the transfer of safe-area signals into an annunciator with IS input terminals
not segregated from each other.
The output–relay contacts are certified as non–energy–storing apparatus, and can be connected
to any IS circuit without further certification, provided that separate IS circuits are such that
they would remain safe if connected together.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
IS relay
IS relay
1
Vs–
Vs+
20 to 35V dc
+
–
2
+
–
Control
20 to
35V dc
+
–
+
–
Loop
powered
Contact
inputs
All contacts shown
in normal position
(relays de-energised)
1
2
Sw4
Hazardous area
Safe area
Terminal
Function
1
IS relay output 1 (normally open)
2
IS relay output 1 (normally closed)
3
IS relay output 1 (common)
4
IS relay output 2 (common)
5
IS relay output 2 (normally closed)
6
IS relay output 2 (normally open)
8
Relay 1 cve
9
Relay 1 control –ve
10
Relay 2 cve
11
Relay 2 control –ve
13
Supply –ve
14
ve
OFF position
ON position
1 2 3 4
Table 6 .3:
Switch settings
for modes
Mode
Function
SW1
SW2
SW3
SW4
Contact/Logic
Input
2 ch
Off
On
On
On
1in2out
On
On
On
On
Loop Powered
2 ch
Off
Off
Off
Off
Figure 6 .16:
Top label
for MTL5526
