2201Q4JE-MY-C9-N_2018.01.
Chapter 1 Safety
Compound 2-stage Screw Compressor 4032**C
1.4
Safety Devices
1-7
1.4.3 Compressor Protective Devices
Be sure to adjust the set values and check operation of the protective devices at the
commissioning.
Overview/Function/Purpose
These protective devices are used to protect this product.
Protecting from discharge temperature rise (DT)
This device activates and stops the compressor operation when the compressor discharge
temperature gets equal to or higher than the set value.
Install a temperature sensing port to the discharge pipe.
Protecting from oil temperature rise (OT)
This device activates and stops the compressor operation when the compressor oil
temperature gets equal to or higher than the set value.
Install a temperature sensing port to the oil supply pipe of the package unit (after the oil
cooler).
Protecting from high pressure (HP)
This device activates and stops the compressor operation when the compressor discharge
pressure gets abnormally high due to mishandling of the compressor or suspension of water
supply to the condenser. This device prevents explosion of the equipment and components.
Install a pressure sensing port to the discharge pipe.
Protecting from intermediate pressure (IP)
This device activates when the intermediate pressure of the compressor gets equal to or
higher than the set value and properly controls the compressor. In some cases, this device
stops the compressor operation. Install a pressure output port to the package unit's
intermediate gas pipe (or compressor's intermediate gas pressure output port).
Protecting from suction pressure drop (LP)
This device activates and stops the compressor operation when the compressor suction
pressure gets equal to or lower than the set value.
Install a pressure sensing port to the suction pipe.
Protecting from oil pressure (OP)
This device activates and stops the compressor operation when the differential pressure to
supply oil to the compressor (= lubrication oil supply pipe pressure
−
compressor discharge
pressure) gets equal to or lower than the set value, due to insufficient lubricant, clogged filter
or mixture of refrigerant into the lubrication oil. This device prevents the sliding portion from
being abnormally worn or seized.
Install a pressure sensing port to the package unit's oil supply pump (after the oil pump) and
the discharge pipe.
Protecting from motor over-current (OCR)
This device activates and applies appropriate control when the current gets equal to or higher
than the set level flows. In some cases, this device stops the compressor operation.
This device is normally installed inside the control panel.