TM
INSTALLATION GUIDE
H740
opEration
The H740 is a current-sensitive transducer that monitors current (amperage) in the
conductor passing through it. The integrated relay provides On/Off control. The status
output is suitable for connection to building controllers or other appropriate data
acquisition equipment operating at up to 30 volts. The H740 requires no external
power supply to generate its output.
troublEshooting
Problem
Solution
No Reading at Controller
• Check for control power at sensor (<30 V; <1.0 A)
• Check for amperage in monitored conductor (>0.5 A)
Relay chatters or will not
change state
• Ensure that not more than 24 VAC/DC has been applied to
the coil.
• Parallel applications with AC transformers can damage the
relay. Use appropriate snubbing device.
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
> 200 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.
< 0.5 A (Sensor Min.)
4x
0.5A
0.2 A
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.
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