VERIS INDUSTRIES
INSTALLATION GUIDE
H949
opEration
The H949 is a current-sensitive switching device with integral command relay that
monitors current (amperage) in the conductor passing through it. A change in
amperage in the monitored conductor that crosses the switch (setpoint) threshold
plus the hysteresis value will cause the resistance of the status output to change
state, similar to the action of a mechanical switch. This status information can be fed
back to a building controller that interprets the signal and separately switches the
relay. The status output can also be used to switch the relay directly.
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 H949 relay requires a 12VDC external power supply
for operation.
The H949 housing offers unprecedented mounting flexibility. The mounting bracket
can be attached in three different places. Additionally, the bracket is compatible with
the Veris AH01 DIN Rail clip, allowing DIN mounting.
notEs
troublEshooting
For load currents less than sensor minimum rating:
Wrap the monitored conductor through the center hole and around the sensor body
to produce multiple turns through the "window." This increases the current measured
by the transducer.
4x
1A
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
> 135A (Sensor max.)
For load currents greater than sensor maximum rating:
Use a 5 Amp (H68xx series) Current Transformer (CT) as shown.
Problem
Solution
No Reading at Controller
• Check sensor calibration (see above)
• Check for control voltage at sensor (<30V)
• Check for amperage in monitored conductor (>2.5A)
• Assure that sensor core mating surfaces are clean and
that the core clamp is completely closed
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.
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
A. To monitor under-current (belt loss, coupling shear, status)
A
OK!
!
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.
B. To monitor over-current (mechanical problems, seized impeller)
A
OK!
!
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.
OK!
STATUS
OK!
STATUS
Setpoint
Status
Open
STOP
Setpoint
Status
Closed
STOP
1/4
Setpoint
+
Setpoint
Status
Closed
STOP
Setpoint
Status
Open
STOP
+
1/4
Setpoint
Before beginning calibration, establish normal load conditions.
OK!
A
OK!
Then choose either A or B below.
Controller must be
programmed to account for the
extra turns. e.g., if four turns
pass through the sensor (as
shown) the normal controller
reading must be divided by 4.
< 2.5 A (Sensor Min.)
240A
300A:
5A
4A
www.calcert.com
1.800.544.2843
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