Hanna Instruments HI 7871 User Manual
Instruction Manual
95mm MIN
3.74"
76mm
3"
0.25/4mm
0.01/0.160"
79mm
3.11"
ADJUSTABLE
LOCATION
BRACKET
HI 7871- HI 7873
HI 7874
Level Controllers
Dear Customer,
Thank you for choosing a Hanna product.
This manual will provide you with the necessary information
for a correct operation.
If you need additional technical information, do not hesitate
to e-mail us at tech@hannainst.com.
These instruments are in compliance with the directives.
PRELIMINARY EXAMINATION
Remove the instrument from the packing material and examine it carefully. If any damage has occurred during shipment,
immediately notify your Dealer or the nearest Hanna Customer
Service Center.
Note: Conserve all packing material until the instrument has
been observed to function correctly. Any defective item
must be returned to the Dealer in its original packing.
FUNCTIONAL DESCRIPTION
FRONT PANEL
1
2
3
REAR PANEL
1. OVER LED (HI 7873 only)
indicates an overflow condition
2. HIGH LED indicates full tank
4
3. LOW LED indicates low liquid
level
4. 11-pin socket
SPECIFICATIONS
HI 7871 HI 7873
Transmission max 100 m (330 feet)
Electrical Connection* HI 7164 undecal connector
Level Adjustment high, low high, low, overflow
Level Indication high, low high, low, overflow
Sensing Bars* 34
Transmitter* HI 7874
Output Contact 1 relay 2 relays
(2A/250 Vac, 30Vdc)
Power Supply 110/115 Vac or 220/240 Vac; 50/60 Hz
Environment 0 to 50°C (32 to 122°F);
RH max 85% non-condensing
Dimensions 83 x 53 x 95 mm (3.1 x 1.9 x 3.7")
Weight 250 g (8.8 oz.)
* Not included with HI 7871 and HI 7873.
www.hannainst.com
WARRANTY
HI 7871, HI 7873 and HI 7874 are warranted for two years
against defects in workmanship and materials when used for their intended purpose and maintained according to instructions. This warranty is
limited to repair or replacement free of charge.
Damages due to accident, misuse, tampering or lack of prescribed maintenance are not covered.
If service is required, contact the dealer from whom you purchased the
instrument. If under warranty, report the model number, date of purchase,
serial number and the nature of the failure. If the repair is not covered by
the warranty, you will be notified of the charges incurred. If the instrument
is to be returned to Hanna Instruments, first obtain a Returned Goods
Authorization Number from the Customer Service department and then
send it with shipment costs prepaid. When shipping any instrument, make
sure it is properly packaged for complete protection.
All rights are reserved. Reproduction in whole or in part is prohibited
without the written consent of the copyright owner, Hanna Instruments.
Hanna Instruments reserves the right to modify the design, construction
and appearance of its products without advance notice.
GENERAL DESCRIPTION MECHANICAL DIMENSIONS
HI 7871 and HI 7873 are 2-wire transmitter level controllers
designed especially for long distance control of liquid levels in
tanks (e.g. in biological and industrial water treatment).
A complete system should include:
• HI 7871 or HI 7873 level controller
• HI 7874 level transmitter & bar holder
• HI 7164 undecal connector
• 3 or 4 measuring bars
The level transmitter is basically a molded electrode holder
with 4 sockets to screw in the level sensors. The longest bar
has to be the common electrode and connected to the COM
port. The remaining bars can be connected in any sequence,
after cutting them to the required lengths.
HI 7874 contains a completely resinated amplifier circuit and
a 2-wire terminal board. It also comes with a mounting
bracket for quick and easy installation.
HI 7874 uses stainless steel measuring bars and employs 9V
peak to peak AC to measure the liquid level. It can be used
in liquids with conductivity greater than 10 µS/cm.
HI 7871 requires only 3 bars, whereas HI 7873 needs 4.
HI 7871 is a basic high and low level controller. HI 7873 has
an additional overflow alarm control.
FRONT VIEW
73mm
79mm
2.87"
3.11"
42mm
1.65"
49mm
1.93"
SIDE VIEW
The supplied adjustable brackets allow the controller to slide
into the cut-out and hold the unit in place. 95 mm (3.74")
is the minimum space required to install the controller with
the cables connected.
CONNECTIONS
• Remove the 11-pin connector from the rear of the level
controller.
• Connect a 2-wire power cable to terminals #2 and #7
(no ground connection).
• Connect the output terminals #4 (common) and #5
(low) to a relay switch (max 2A/230V) to start and stop
a pump or to open and close an electrovalve. These two
contacts act only as a switch and the pump or electrovalve
have to be powered independently.
OPERATIONAL GUIDE
• Turn on the power supply. After approx. 8 seconds, the
controller can activate a pump or electrovalve.
• When liquid level is below the COM (reference) or the 1
bar, LOW LED turns on and output contacts (#4 & #5)
close, activating a pump/electrovalve.
• Subsequently, when liquid level drops below the 3rd bar,
OVER LED goes off and HIGH LED comes on. When liquid
CE DECLARATION OF CONFORMITY
level drops below the 2nd bar, HIGH LED goes off. LOW
LED lights up when the level drops below the 1st bar.
st
• HI 7873 can also detect faulty conditions, such as a short
or open circuit, in the 2-wire connection between #8 and
#9 terminals with HI 7874 bar holder.
The common terminal (#4) and #3 can also be connected to a device to indicate a “full tank” state.
• With HI 7873, connect termi-
nals #10 and #11 to an
alarm for monitoring Over Flow
condition.
• Remove the cover of HI 7874 (bar holder) and connect a
2-wire cable from #8 to positive (+) and #9 to
negative (–) terminals of the holder.
• Screw the longest bar to the hole
marked as COMM. This bar will be
used as the reference electrode. Screw
the other measuring bars into the
remaining sockets in any order. The
bars should be cut to the required
lengths for low, high and over. The
reference (COM) and the low bar
(1st) can be the same length.
• With HI 7871, connect only 3 bars
to the holder: reference, low and
high. With HI 7873, connect 4 bars
to the holder: reference, low, high
and over.
• Insert the 11-pin connector to the
back of the level controller.
• When liquid level reaches the low (1st) bar, LOW LED goes
off but the contacts (#4 & #5) remain closed.
• When liquid level reaches the high (2nd) bar, HIGH LED
turns on and the output contact (#5) opens (pump/
electrovalve disactivated) while #3 & #4 close.
• With HI 7873, if after reaching HIGH level, liquid level
continues to rise and reaches the 3rd bar, the alarm
contacts close and the OVER LED comes on.
If the 2-wire is shorted, the OVER LED
goes on and the alarm contacts close.
If the 2-wire is damaged and the circuit
is open, LOW LED goes on and the alarm
contacts close.
• With HI 7871, LOW LED goes on with an
open circuit. If the LOW LED remains lit
but the pump/electrovalve is not activated, it indicates an open circuit.
A short circuit will instead give a HIGH
LED indication.
Note: It takes about 8 seconds for the controller to activate
the relay from when an alarm condition occurs.
ACCESSORIES
HI 7164 Undecal connector
HI 7875/P Stainless steel threaded measuring bars (5 pcs)
Note: The sensing bars are made in such a way that they
can be screwed one into each other to provide any
required length. It is recommended to keep the bars
separate with a non-conductive material, such as
plastic to ensure they do not touch each other, specially in deep tanks.
Recommendations for Users
Before using these products, make sure that they are entirely suitable for the environment
in which they are used.
Operation of these instruments in residential areas could cause unacceptable interferences
to radio and TV equipment.
Any variation introduced by the user to the supplied equipment may degrade the instrument's
EMC performance.
For HI 7874 only:
The measuring bars at the end of the sensor are sensitive to electrostatic discharges. Avoid
touching these bars at all times.
Connection to level controller should be done with the recommended ferrite close to level
controller.
IST7871R2 06/05
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