ENMET ISA-40M - Manual (Page 11)

ISA-40M Oxygen Monitor ENMET Corporation
9
3.3.1 Non-Latching Relays
There is one non-latching, single pole relay per channel. These relays furnish normally open, normally closed, and
common terminals, which are available on TB3 and TB4; refer to the motherboard drawing. These relays are fail-safe;
the power off position and the alarm position of the contacts are identical. Contact positions are given for the power
off, alarm condition.
Table 3: Non-Latching Relay Wiring
Non-powered, alarm positions are given
Channel Terminal Position Contact
1 TB3 – 1NC Normally closed
1 TB3 – 1NO Normally open
1 TB3 – 1COM Common
2 TB3 – 2NC Normally closed
2 TB3 – 2NO Normally open
2 TB3 – 2COM Common
3 TB4 – 3NC Normally closed
3 TB4 – 3NO Normally open
3 TB4 – 3COM Common
4 TB4 – 4NC Normally closed
4 TB4 – 4NO Normally open
4 TB4 – 4COM Common
3.3.2 Latching Relays
Latching relays are available on TB7, the terminal strip located on the auxiliary relay circuit assembly located on the
upper surface of the control unit enclosure. These relays, once triggered by an alarm condition, remain latched in the
alarm position until released by an operator, who activates the relay release pushbutton switch on the front of the
enclosure. This switch releases all latched relays together. These relays are not failsafe; the power off position of the
contacts is opposite from the latched alarm position. The contact positions given are for the power off, non-alarm
condition
Table 4: Latching Relay Wiring
Contacts are in non-powered, non-alarm position
Channel Terminal Position Contact
1 TB7 – 1 Normally closed
1 TB7 – 2 Normally open
1 TB7 – 3 Common
2 TB7 – 4 Normally closed
2 TB7 – 5 Normally open
2 TB7 – 6 Common
3 TB7 – 7 Normally closed
3 TB7 – 8 Normally open
3 TB7 – 9 Common
4 TB7 – 10 Normally closed
4 TB7 – 11 Normally open
4 TB7 – 12 Common