Model 2280A
14
CAUTION:
Inductive loads, such as bells, buzzers, relays, contactors, solenoid
valves, etc., connected to the high alarm, low alarm and fault alarm
relays must be clamped down as shown in the diagrams below.
Unclamped inductive loads can generate voltage spikes in excess of
1000 Volts. Spikes of this magnitude will cause false alarms and
possible damage.
Figure 4: Protection Circuit for Relay Contacts
2.9 Multiple Controller Operation
Up to sixteen points of gas detection utilizing one set of alarm relays may be
configured by interconnecting the “=”, “H”, and “M” terminals of TB2 at the rear of four
Model 2280A controllers. Each Specific terminal, such as the “H” terminal, is
connected from controller to controller using 20AWG wire (or larger). The controllers
must be installed adjacent to each other, and the interconnecting wires kept as short
as possible. By using two or three Model 2280A controllers, respectively, the same
method may be used to interconnect eight or twelve sensors (Figure 10).