Carrier 30KAV-ZE Series Installation, Operation And Maintenance Instructions page 43

6 - MAJOR SYSTEM COMPONENTS
6.1.8 - High Pressure SRMCR safety loop
General description
The unit is equipped with a high pressure safety loop, known as
the SRMCR (Safety-Related Measurement Control and
Regulation) loop, comprising:
■ 2 high pressure switches (HPS) that require resetting with a
tool at the outlet of each compressor called PZHH.
■ The speed regulator which supplies the compressor and is
equipped with the Safe Torque Off (STO) function.
Refer to the wiring diagram and the nomenclature for the machine
(references).
This SRMCR device is designed in accordance with standard
EN 61508 for SIL (safety integrity level): 2.
Demand mode: Low and high.
The mission time is 20 years.
Periodic testing: The test must be performed at least once a year
during the normal periodic pressure test. Refer to the description
in section 10.8.4.
Description of operation and resetting
The image below is intended to illustrate the operating description:
Refer to the detailed machine drawing for the precise wiring
diagram.
Pressure increase
Direction of operation
Pressure increase
Direction of operation
Normal Com bus for
start-stop frequency
setting
GS_1 drive
HPS: High pressure switch SP1F(A)/SP2F(A)
GS_1: Power drive for compressor GSA1/GSB1
During normal operation, the speed regulator supplies and
controls the compressor once the control signal is received via
the digital on-off input (normal on-off) and the communication bus
(setting the frequency).
When one of the HPS sensors opens, the STO (Safe Torque Off)
digital input opens, which instantly suppresses the control
command for the thyristors which manage the supply for the
compressor, independently of the on-off commands and
frequencies: The compressor is no longer supplied and stops
immediately.
HPS SP_F
HPS SP_F
400 VAC
STO Input
PLd- SIL2
Compressor
06Z
Restarting after high pressure detection
After overpressure is detected, it is necessary to manually reset
the switched HPS. A blunt tool with a diameter of less than 6 mm
must be used for this.
Verification in case of a safety device failure
If the unit operating pressure appears to have been exceeded at
some point (for example, after the relief valves have been opened),
the unit must be stopped immediately.
The safety loop unit must pass all the periodic verifications before
any restart is possible.
If the test reveals malfunctions likely to have caused overpressure
within the machine, a complete check of all the pressure equipment
must be performed to check their mechanical integrity.
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