Caution, Installation guide, Operation – Veris Industries H708 Install User Manual
Page 2: Troubleshooting, Calibration, H708
Z201484-0E
PAGE 2
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01121
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TM
INSTALLATION GUIDE
H708
OPERATION
The H708 is a current-sensitive switching device that monitors current (amperage) in
the conductor passing through it. A change in the conductor’s amperage that crosses
the adjustable switch threshold plus the hysteresis value causes the resistance of
the FET status output to change state, similar to the action of a mechanical switch.
In this model, the setpoint is adjustable through the action of a twenty (20) turn
potentiometer (see the CALIBRATION section). The status output is suitable for
connection to building controllers or other appropriate data acquisition equipment
operating at up to 30 volts. The H708 requires no external power supply to generate
its output.
TROUBLESHOOTING
Problem
Solution
No Reading at Controller
• Check sensor calibration (see above)
• Check for control voltage at sensor (<30 V, <1.0 A)
• Check for amperage in monitored conductor (>1 A)
Setpoint screw has no
stops
The setpoint screw has a slip-clutch at both ends of its travel to
avoid damage. Twenty turns CCW will reset the sensor to be
most sensitive. Repeat calibration above.
Both LEDs are lit
Setpoint screw is too far clockwise. See solution above.
4x
0.5A
DANGER: 5A CTs can present hazardous voltages.
Install CTs in accordance with manufacturer's instructions.
Terminate the CT secondary before applying current.
H68xx‑5A CT
240A
300A:
5A
> 135 A (Sensor max.)
CAUTION
RISK OF EQUIPMENT DAMAGE
• Derate the product’s maximum current for the number of turns
through the sensing window using the following formula.
Rated Max. Amps ÷ Number of Turns = Max. monitored Amps
e.g. : 100A ÷ 4 Turns = 25 Amps max. in monitored conductor
• Failure to follow these instructions can result in overheating
and permanent equipment damage.
CALIBRATION
Before beginning calibration, establish normal load conditions.
OK!
A
OK!
Then choose either A or B below.
< 1 A (Sensor Min.)
A. To monitor under-current (belt loss, coupling shear, status)
A
OK!
!
B. To monitor over-current (mechanical problems, seized impeller)
A
OK!
!
OK!
STATUS
OK!
STATUS
1. Turn setpoint screw
clockwise until Status Open
LED turns ON.
2. Slowly turn the screw counter-clockwise until the Status Closed LED just
turns ON.
3.Turn the screw an
additional 1/4 turn
counter-clockwise for
operational margin.
Setpoint
Status
Open
STOP
Setpoint
Status
Closed
STOP
1/4
Setpoint
+
3. Turn the
setpoint screw
an additional 1/4
turn clockwise
for operational
margin.
1. Turn setpoint screw
counter-clockwise until Status
Closed LED turns on.
2. Slowly turn the setpoint screw clockwise until the Status Open LED
just turns on.
+
1/4
Setpoint
Setpoint
Status
Closed
STOP
Setpoint
Status
Open
STOP
NOTES
For load currents greater than sensor maximum rating:
Use a 5 Amp (H68xx series) Current Transformer (CT) as shown. This technique can be
combined with wrapping (see below) to add range for a low current load on a high
current source.
For load currents less than sensor minimum rating:
Wrap the monitored conductor through the center window and around the sensor
body to produce multiple turns. This increases the current measured by the
transducer.