HF scientific Micro200BW Turbidimeter - 0-100 NTU - Manual (Page 23)

MICRO 200 BW 0-10 & 0-100 NTU (05/05)
Rev. 3.4
Figure 9
Remove jumper J-13 to establish isolation
of the 4-20mA signal.
WARNING: While the chance is slight, there are fault
conditions under which a hazardous volt-
age could be exposed on the analog output
wires when the jumper J13 is removed.
To preclude this possibility HF scientific
strongly recommends, for personal pro-
tection, that a Ground Fault Circuit Inter-
rupter (GFCI), such as LEVITON part
number 6599 or 5299, be used at the power
connection.
2.4.7 Alarm Contacts
Connections are provided to the alarm relay contacts on
the terminal block labeled ALARMS.
NOTE: These are “fail safe” and will revert to an “alarm”
condition should the power be disconnected, for
any reason.
Refer to the Specifications to ensure that alarm contact
ratings are not exceeded.
NOTE: ALARM 1: Terminal Block J1
ALARM 2: Terminal Block J2
SENSOR ALARM: Terminal Block J3
The following are the connections for each of the relay
contacts:
Terminal 1: Normally Closed (N.C.) (open on alarm)
Terminal 2: Normally Open
(N.O.) (closed on alarm)
Terminal 3: Common (C)
WARNING: Ensure that all external voltages in excess
of 30 volts are disconnected before at-
tempting to make connections or discon-
nections from alarm terminal blocks.
The SENSOR ALARM contacts are provided to indicate
that the source lamp in the sensor module has failed or that
the MICRO 200 BW requires routine standardization.
NOTE: For external analyzer connection, other than
power, #14 AWG is the largest wire the connect-
ing terminals will accept.
2.4.8 Cable Mounted Ferrites
The interconnect cable has a cable mounted ferrite on it,
located near the analyzer. To maintain the CE rating for
EMI this ferrite HF #21140 must be in place when
operating the instrument.
Some input/output connections that are made to the
Micro 200 BW will also require the addition of a ferrite
to maintain the CE rating for EMI. The following
connections require the addition of HF# 21138: Serial
Ports, Recorder Output - Current (4-20mA), Recorder
Output - Voltage.
2.5 TURBIDITY SENSOR
2.5.1 Interconnect Cable
The interconnecting cable from the analyzer is plug
connected at the sensor. If the interconnecting cable is
removed at the analyzer end, it should be reconnected
to terminal block labeled SENSOR INTERFACE (J8).
The cable wire colors are labeled in front of this terminal
block.
2.5.2 Inserts for Sample & Drain Lines
Plastic inserts (not needed with rigid tubing) are pro-
vided with the turbidity sensor and are intended for use
with 5/16" OD x 3/16" ID (7.94 mm OD x 4.76 mm ID)
flexible plastic tubing as sample and drain lines.
3.0 STEP-BY-STEP OPERATION
3.1. THEORY & HOW IT WORKS
The HF scientific, inc., MICRO 200 BW Turbidimeter
is specifically designed to monitor turbidity and back-
wash water in water filtration plants. This is done by
providing a linear display of turbidity in Nephelometric
Turbidity Units (NTU). The units, FTU and NTU, are
compatible. Optional backwash function is displayed
in Percent Transmission (% T).
The MICRO 200 BW is a continuous reading Nephelo-
metric instrument that measures scattered light from
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