Fluid Components International FLT Series Rack Mount - Manual (Page 31)

FLUID COMPONENTS INTL CHAPTER 5 - TROUBLESHOOTING
FLT  Series FlexSwitch  Rack Mount 5 - 2 Doc. No. 06EN003250 Rev. N/C
For Factory Calibrated Instruments, Check the Application Data Sheet (ADS)
Design problems usually occur with first-time applications. If the Application Data Sheet does not match the
instrument's actual process conditions, errors occur. See the plastic sleeve at the back of the manual for a copy of the
ADS.
1. Review the instrument's ADS with plant operation personnel and plant engineers.
2. Verify that the process media, as well as the range of process temperature and pressure, agrees with the
instrument's ADS.
Verify the Sensing Element Resistances
The following procedure provides a step-by-step checkout. The measurements are based on a standard sensing
element (1.1K ohm RTDs at 80°F). Variation of ±500 ohms from nominal is to be expected. The maximum
allowable difference in resistance between matched RTDs is 1% at ambient temperature (immersed in water). The
heater resistance should be 110 ±5 ohms for the S model sensing element and 560 ±13 ohms for the F model sensing
element.
Check the Resistance at the Control Circuit Connector
Warning: Turn the instrument's power OFF.
Gently remove the control circuit from the rack. Use a multimeter to measure the resistance of the sensing element's
heater and RTDs (see Tables 5-1 and 5-2 for nominal values).
Note: If enough time has not been allowed for the sensing element to cool, then the resistance of the active
RTD will be greater than the resistance of the reference RTD.
Table 5-1. Matrix of Nominal Resistance Values (ohms at 80°F) at P1 CH. A
Pin No.
P1-B10
(ACT)
P1-D8
(COM)
P1-D10
(REF)
P1-Z8
(HTR +)
P1-B8
(HTR RTN)
P1-B10
(ACT)
0 1.1K 2.2K OPEN OPEN
P1-D8
(COM)
1.1K 0 1.1K 1.3K OPEN
P1-D10
(REF)
2.2K 1.1K 0 2.4K OPEN
P1-Z8
(HTR +)
OPEN OPEN OPEN 0
110 S MODEL
560 F MODEL
P1-B8
(HTR RTN)
OPEN OPEN OPEN
110 S MODEL
560 F MODEL
0