DC transducer protectors provide continuous surveillance of the dc
process voltage or current signal. When the standard process signals
move outside the set point limit the relay will operate. Combining the
protection relay with a measuring transducer such as the Crompton
Paladin measuring transducers range can form specialised control
products whenever self-contained relays are not available.
Operation
The dc transducer protector relay offers user adjustable trip point (set point) and time
delay settings. The time delay setting adjustment range is typically 0 to 10 seconds,
although longer delays are available. As soon as the monitored signal moves outside of
the set point limit the time delay is activated, after which a trip will occur. The time
delay prevents the relay from tripping for a predetermined period to prevent nuisance
tripping. The products also feature an internal differential (hysteresis) setting of 1% to
reduce nuisance tripping if the measured signal is noisy or unstable. These units require
an auxiliary power supply.
Over High Trip Models
When the monitored signal exceeds the set point, the time delay is started. When the
time has elapsed, the relay will energise and the red LED will illuminate to indicate the
trip condition. The relay will automatically reset once the monitored signal falls below
the set point minus the differential. When reset, the LED will extinguish and the relay
de-energises. The time delay is not active when resetting.
Under Low Voltage Models
When the monitored signal falls below the set point, the time delay is started.
When the time has elapsed, the relay will de-energise and the red LED will extinguish
to indicate the trip condition. The relay will automatically reset once the monitored
signal rises above the set point plus the differential. When reset, the LED will illuminate
and the relay energises. The time delay is not active when resetting.
Options
250 series protector relays offer various customised options to suit individual
requirements.
- Adjustment ranges – different adjustment ranges are possible for the set point and
time delay controls.
- Differential – internally fixed value between 1% and 15%.
- Relay operation – standard models are fail safe, but the relays can be customised
to energise or de-energise on trip.
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