ATI
PQ45P pH System
Part 4
– Electrical Assembly
13
O&M Manual
Rev-B (7/15)
operation will be limited to about 10 days
on a charge. However, NiMH batteries
can be recharged hundreds of times.
The third switch assembly is a single slide switch
(S3)
which defines whether the
0-2.5 VDC signals from the monitor are isolated or non-isolated. Output isolation
is not required when outputs are connected to the internal data logger. However,
if the outputs are connected to external devices through the external connection
cable, putting this switch in the ISO position will protect against possible ground
loops. The isolation circuit will slightly increase the power requirement for the
monitor, resulting in a bit less battery life.
3.4
External Power / Output Connections
PQ45H units ordered with the external connection option are designed for applications where
power is to be supplied from an external source, and the two voltage outputs are to be wired to an
external device. If that option has been supplied, an interface cable will be provided.
Figure 7 below identifies the terminal connections for external power and voltage outputs. These
terminal are factory wired to a connector on the side of the case, and are connected to the
outside using the supplied interface cable.
Figure 8 below identifies the color code for signals carried by this interface cable. External power
is connected to the red and black wires. The other conductors carry the voltage outputs.
Figure 7 - Battery Circuit Board w/External Power Terminals
Figure 8 - External Connection Cable Color Code
