Type 202 Electronic Unit Specification
Enclosure:
Wall mounted glass-fibre reinforced polyester, offering IP65/NEMA4X
protection for location in harsh environments.
Dims: 320H x 200W x 120D (mm)
Inputs:
Discrimination between water and steam for 14 independent channels numbered in ascending order. Discrimination threshold may be selected for minimum water conductivities of, 0.5, 1 or 2mS/cm. The lower 8 probe channels have a single wire connection to the probe and the upper 6 channels have a two wire connection to each probe. Any wire disconnection on the lower Probes
reverts the channel to steam indication if the probe is immersed in
water and any disconnection on the upper Probes reverts the channel
indication to water if immersed in steam ; this facility enhances
fault declaration by way of a Yellow flashing LED.
Power Supply:
The system uses two independent AC sources:
90 - 265 Volts AC @ 15 VA, 48 - 63Hz
The 202 unit provides improved operational integrity in the
event of one Mains supply failure by the unique method of
implementing DC supplies to the electronic circuitry.
Display:
The unit incorporates a Two vertical column display of 10mm square LED's
on the front of the enclosure. The green LEDS represent water and Red
LED's represents steam. Particular LED's can be selected to flash on
initiation of Alarm levels.
A Yellow LED flashes for a fault state.
Outputs:
Alarm/Trip Relays. Four sealed relays, each having
Singlepole changeover contacts provide Alarm and Trip signalling.
Each relay may be programmed for the normally energised or de-energised
state with delay action period of 0, 5, 10 or 15 secs.
Two relays for low and high level alarms may be linked to channels
in the range 3 to 6 and 9 to 12. A low and high channel may be linked
to the relay for a combined Lo/Hi alarm.
The two trip relays provide low level and high level trip initiation.
A 2 out of 3 Probe channel voting circuit is applied with a 4th channel
backup to counter internal supply failure. The normal Lo Trip level
may be selected for channel 2 or 3 and the Hi-Trip level for channel
12 or 13.
Contact rating: 350 Volts 5 Amps.
Max. Switching Power: AC-600VA
DC- 30W / 110V, 120W / 30V
(ii) Remote Display. Twenty terminals are provided for direct connection
to a Remote Display unit.
(iii) 4/20mA Transmission Signal: An integral 4 to 20mA circuit where
each probe channel contributes a step change of 1.14mA. Selection
of 4mA to represent the all water or all steam state. Max Load Impedance: 300 ohms
(iv) System Fault Alarm. A single pole changeover contact is available
signalling supply failure or Probe channel malfunction by validation
between adjacent channels.
Remote Display Unit Options:
Type 20251A. Panel mounted IP20
Dims: 180H x 72W x 30D (mm)
This unit duplicates the display on the front of the main unit as
is intended for control room location. Panel Cutout Dims: 174 x 67 (MM); 1.5 to 6.5mm thick
Type 20252 Plant mounted IP65.
Dims: 160H x 80W x 60W (mm))
Low consumption 5mm LED's
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12 or 14 Probe Ports