Powtier Controls Limited
505MST Thermostat
Instruction Manual
Technical specification
POWER SUPPLY
Voltage
70Vdc to 130Vdc; 110Vdc nominal
Ripple
Unaffected by 4 volt peak to peak
Input protection
Reverse polarity protection. Surge and transients to
BRB/RIA 12
Current consumption
100mA maximum at 110Vdc
SENSOR
Saloon sensor
Platinum resistance PT100 to BS1904 class B; sensor error
/-0.3°C; two wire and sensor leads must be less
than 5 meters
Lead resistance error
If sensor lead greater than 5 meter is used - lead resistance
input compensation is required. This is achieved by means
of an "offset-value" in software in the microcomputer
Screened cable
Sensor cable wires must be screened and connected to the
system earth
Interchangeability
Temperature
probes
are
easily
detachable
and
interchangeable with sensor error altered by not more than
+/-0.3°C
Time constant
20 to 40 seconds when the sensor is subject to an air
stream of 2m/s
INDICATORS
Heat 3 output
Red LED; illuminates when heat 3 is ON
Heat 2 output
Red LED; illuminates when heat 2 is ON
Heat 1 output
Red LED; illuminates when heat 1 is ON
LLDS output
Yellow LED; illuminates when LLDS is ON (energised);
(LLDS: Lower Lever Damper Solenoid)
COOL output
COOL LED; illuminates when cool is ON
Winter/Summer
Green LED; illuminates during summer period
DC supply
At least one of the LEDs would be ON when the DC
supply is connected
OUTPUT SWITCHING
Relays
Five relays, change-over, normally open contacts: Schrack
RP330024, single pole
Contact rating
250Vac, 16Aac; 440Vac, 100mAac
Mechanical life
Greater than 30 million operations
Electrical life
Greater than 1 million operation at 440Vac, 100mAac
OUTPUT SWITCHING
Accuracy
+/-0.2°C of each setpoint temperature
Hysteresis
1.0 +/-0.1°C; for example, Heat 1 setpoint is 18.5°C, it
would switch of at 18.5°C on rising temperature and off at
17.5°C on falling temperature
Maximum drift
+/-1.0°C over operating temperature range of -25°C to
50°C
505MSTIM
Page 13
29 June 1998
Issue 1.0