Microtel Series 100 - Manual (Page 11)

G. FAULT MONITORING INTERFACE CONNECTIONS
The MCS system is designed to accept up to eight channels of dry (unpowered),
normally open or normally closed signal lines. The system provides a small sampling
current to determine if the contact is open or closed. Leads from normally open or
normally closed switches may be routed through the conduit port at the lower right
side of the system. Connect each wire pair to its appropriate channel input terminal
pair on the Fault Interface Assembly card. Shielded, twisted pair, F20 or F22 wire
(Belden 8205 or equivalent) is recommended. If shielded cable is used, ground the
shield at the sensor and leave the shield floating (unconnected) at the MCS system.
Each channel must be configured to be either normally open or normally closed. A
channel should be normally open if the "no fault" condition is that condition which
consists of an open circuit on that channel's wire pair. A channel is normally closed if
the "no fault" condition is that condition which consists of an closed circuit on that
channel's wire pair.
An eight-position DIPswitch is provided to set the state of each channel to a normally
open or normally closed configuration. When the switch associated with a channel is
in the OPEN or OFF position, that channel is configured as a normally closed
channel i.e., a closed fault switch is a no fault condition. When the switch associated
with a channel is in the CLOSED or ON position, that channel is configured as a
normally open channel i.e., an open fault switch is a no fault condition. For each
channel, as indicated on the Fault Interface Assembly card, program the switch
associated with that channel to the desired state.
Adjustable potentiometer R35, located on the opposite end of the fault interface card
from the DIP selector switch, labeled Fault Integrate, controls the length of time it
takes for the system to recognize a fault condition, regardless of whether it is
configured as a normally closed or normally open channel. The time may be user set
for one second minimum to one minute maximum. The relative timing may be viewed
by watching the indicator CR13. The actual integration time is four times the flashing
rate of CR13.
Any unused channels should be programmed a normally open, and left unconnected.
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