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Safety Manual SIL KCD2-STC-(Ex)1.HC(.SP), HiC2025HC
Proof Test
4
Proof Test
4.1
Proof Test Procedure
According to IEC 61508-2 a recurring proof test shall be undertaken to reveal
potentially dangerous failures that are otherwise not detected by diagnostic tests.
The functionality of the subsystem must be verified at periodic intervals
depending on the applied PFD
avg
in accordance with the data provided in this
manual. See chapter 2.4.
It is under the responsibility of the operator to define the type of proof test and the
interval time period.
With the following instructions a proof test can be performed which will reveal
almost all of the possible dangerous faults (diagnostic coverage > 90 %).
The ancillary equipment required:
• Digital multimeter with an accuracy better than 0.1 %
For the proof test of the intrinsic safety side of the devices, a special
digital multimeter for intrinsic safety circuits must be used. Intrinsic safety
circuits that were operated with circuits of other types of protection may
not be used as intrinsically safe circuits afterwards.
• Power supply set at nominal voltage of 24 V DC
• Process calibrator with mA current source/sink feature (accuracy better
than 20
µ
A)
The entire measuring loop must be put out of service and the process held in
safe condition by means of other measures.
Prepare a test set-up for testing the KCD2-STC-(Ex)1.HC(.SP) device
(
see Figure 4.1 on page 13) or for testing the HiC2025HC device
(
see Figure 4.2 on page 13). Choose the proper input terminals (passive
input or active input) in accordance with the specific application and follow the
steps indicated in the table below.
Restore the safety loop. Any by-pass of the safety function must be removed.
Step No.
Set input value (mA)
Measurement point
Output value (mA)
Across 2-wire Tx (V)
Across 4-wire Tx (V)
1
20.00
20.00
±
0.4
15.1
±
0.4
2.2
±
1.1
2
12.00
12.00
±
0.4
16.1
±
0.4
2.2
±
1.1
3
4.00
4.00
±
0.4
17.1
±
0.4
2.2
±
1.1
4*
23.00
23.00
±
0.4
14.5
±
0.5
2.2
±
1.1
5*
0
< 0.2
19.0
±
1.0
n.a.
6
12.00
* The output value shall detect a Fail High, Fail Low condition.
Table 4.1
Steps to be performed for the proof test
