MPC2000D
Issue 2 22/4/98
Page
23
9.5. Temperature Settings
RTD/Thermistor
This setting range: 'RTD' or 'Thermistor', with a default setting of 'RTD', determines whether Resistance Temperature
Detectors or Thermistors are being used for temperature monitoring. In addition to this setting a change in the setting
of an internal group of dip switches is required, refer to notes given in the MPC2000D Measured Inputs section.
Thermistor Type
This setting, range PTC or NTC is only applicable if Thermistor is set above. It determines whether positive or
negative coefficient Thermistors are being used.
Channel 1 Alarm
This setting, range 100-30,000 Ohms if Thermistors are selected and range 100-240 ohms if RTD is selected
determines the resistance level at which an alarm will occur.
Channel 2 Alarm
This setting, range 100-30,000 Ohms if Thermistors are selected and range 100-240 ohms if RTD is selected
determines the resistance level at which an alarm will occur.
Channel 3 Alarm
This setting, range 100-30,000 Ohms if Thermistors are selected and range 100-240 ohms if RTD is selected
determines the resistance level at which an alarm will occur.
Channel 1 Trip
This setting, range 100-30,000 Ohms if Thermistors are selected and range 100-240 ohms if RTD is selected
determines the resistance level at which an trip will occur.
Channel 2 Trip
This setting, range 100-30,000 Ohms if Thermistors are selected and range 100-240 ohms if RTD is selected
determines the resistance level at which an trip will occur.
Channel 3 Trip
This setting, range 100-30,000 Ohms if Thermistors are selected and range 100-240 ohms if RTD is selected
determines the resistance level at which an trip will occur.
The above settings are adjustable in steps 100 Ohms for Thermistors and 1 Ohm for RTD's.
Thermistor 1,2 or 3 Open Circuit.
This is a protection function that has no setting but the user must be aware of its function. When the thermistors are
open circuited (i.e. a very high impedance value) this function will trip the relay indicating which thermistor is open
circuited.
On occasion when the thermistor is open circuit the relay will instead trip on Channel 1(2 or 3) Trip. This is because
the relay reads the change in the thermistor value, a faster increase will give an Open Circuit Trip whilst a slower
increase will give a Channel 1 Trip. In these circumstances the trip that occurs depends on the external circuit and
cabling used. When the change is not quick enough for the MPC2000D to register an Open Circuit a Channel 1 Trip
is registered first instead. This only occurs if the thermistor type is PTC.
