GEA Searle NSQ Series Installation And Maintenance Instructions Manual

immediately, however if the compressor has run for lessthan 6 minutes it will be prevented from starting for theremainder, i.e. if run for 4 minutes, there will be a 2 minutedelay on the next start. This is non adjustable.Delay on Power Up start FunctionThe timer also has an adjustable delay for start up after amains power failure. This function may be used to give aset delay before the compressor starts, and can be setdifferently on multiple units to prevent an over current onthe mains supply, and possible tripping of the mainsbreaker.To adjust the delay see the diagrams below.The modules have indicator LED’s which illuminate whenthe delay timer is active.Units with Combined Alarm Relay and Anti CycleUnits with separate Anti-Cycle / Alarm Moduleh) Volt Free Alarm Relay – Standard on NSQ/NCQ,optional on NSE NCE, with electrical options W, T & E.Units are fitted with a volt free relay, either mounted on aseparate din rail, or integrated in the Anti-Cycle timer, (seesection ‘g’). The relay will energise when ‘Healthy’ and willde-energise on the following faults :-Mains Power Loss, HP Trip, Compressor Overload Trip.The relay is a changeover type with volt free terminals forNormally Open, Normally Closed and Commonconnections. Any customer connection to these terminalsmust not exceed a load of 8A resistive (AC1) at 230V.‘L’ version units onlyi) DTC - 'LX/S' models use ZF scroll compressors.ZF model compressors require liquid injection to keepdischarge temperatures within safe limits. The compressor isequipped with a sensor bulb, which is installed, in the top capof the compressor. The bulb senses discharge temperatureand enables controlled liquid injection as temperature risesabove the factory set point. The valve is connected with aflexible hose to the liquid line via a schraeder connection.j) Klixon - discharge temperature protector, switches thecompressor off if the discharge temperature exceeds a pre-setmaximum (auto re-set).k) EVI Vapour Injection Solenoids – ‘LV’ models only.Units are fitted with a Plate Heat Exchanger to super sub coolthe liquid from the condenser, and provide vapour injection tothe compressors. A solenoid valve on each compressorvapour injection port is slaved to the compressor contactorsand operates when the compressor runs.All unitsl) Pressure Relief Valve - fitted in the side of the liquidreceiver. If the unit is not located externally in open air therelief valve outlet must be piped away to open air.Regular maintenance is required see section 6.Maintenance Every 3-6 Months.3. EVACUATION AND CHARGINGBefore operating the unit for the first time, check that allguards, motors, mountings and electrical covers are secure,and that fans rotate freely. The unit has been leak tested,dehydrated and filled with a holding charge of "dry air" duringmanufacture.The entire system should be evacuated prior to charging asfollows:• The right hand panel should be removed to provide accessto the compressor shut off valves with service ports.• Connect a vacuum pump to the 1/4" flare connections oneach compressor shut-off valve.• These valves will be in a fully back-seated position in theunit as supplied. The valve spindles should be screwed in afew turns to open up the ports.• Evacuate the system to below 225 microns (0.3mbar). Thepump should be isolated and system pressure monitored. Arapid continuous rise would indicate a leak in the system.• During the evacuation process, the crankcase heatershould be switched on.Note: To ensure that compressor is not operated duringevacuation, the compressor overloads / manual motor startersmust be in the off position.DO NOT START THE COMPRESSOR UNDERVACUUM. NEVER RUN COMPRESSOR IF CONTAININGAIR .The unit should be charged with the specified refrigerant(N2CQ ‘L’ Units R404A, ‘N2CQ M’ UnitsR404A/R407C/R134A), until the sight glass is just clear at thenormal operating condition. If after charging the unit is left withthe power supply turned off, turn on the power supply for aminimum period of three hours before the unit is switched on.This will ensure that the compressor sump is warm and freefrom liquid refrigerant.IMPORTANTN2CQ Scroll compressors, like several other types ofcompressor, will only compress in one rotational direction.Three-phase compressors will rotate in either direction,depending upon phasing of the power to T1, T2 and T3. Sincethere is a possibility of connecting power in such a way as tocause rotation in the reverse direction, it is important to checkthis. Verification of rotation direction can be made byobserving that suction pressure drops and discharge pressurerises when the compressor is energised. Reverse rotationresults in a sound level above that of the correct rotationdirection, as well as a substantially reduced current draw.4