Hofmann PMH-2, Руководство пользователя

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Alarm
A second relay with potential free contacts controlled through config-
ured low and high alarm mV points can be connected to an alarm device
or use the potential free relay contacts for event monitoring or recording
digital data into a central processor system. The relay can also be used
as a second setpoint control output.
Flow-switch
A flow-switch connected to the PMH-2 prevents dosing chemicals if for
any reason the water flow has stopped. Two types of flow-switches exist:
The term “normally open” is used if the contacts are open with flow and
close if flow stops. Select OP mode if this type of switch is used.
The term “normally closed” is used if the contacts are closed with flow
and open if flow stops. Select CL mode for this type of switch.
If it is not certain what type of switch is in the system operate the PMH-2
and configure for OP or CL until normal operation of the relay output is
established with water flowing. If no water flows through the system the
PMH-2 prevents the relay from switching and flashes the green LED.
4-20mA signal output.
The PMH-2 features two modes of operation for the 4-20mA signal
output. In normal operation [nor] a “window” is configured by selecting a
low mV for 4mA and a high mV for 20mA current. The 4mA point is
selected between 000 and 500 mV. The 20mA point is selected between
600 and 1000 mV.
FIG. 8 4-20mA normal Signal current control.
PAGE 24 PMH-2 Instruction manual