air cooled screw water chiller zamil Electrical and Troubleshooting

air cooled screw water chiller zamil

Electrical and Troubleshooting

chiller zamil

: STANDARD SPECIFICATIONS

These chillers are equipped with stepless capacity control system as standard for very accurate response to load requirements and best part load efficiency. Each compressor is equipped with a slider controller that enables to modulate capacity between 25% to 100%, thus giving a broad range to control total chiller capacity between 10% to 100% on an average. This system has following advantages:

1.    Infinite capacity modulation allows the compressor capacity to exactly match the cooling load.

2.    Reduce compressor cycling which leads to better operational reliability.

3.    Reduce operating cost.

 

  Optional settings:

The Zamil packaged chillers incorporate stepped load shedding as required by most energy management systems. Modulation of capacity in response to system load requirements is affected by a microprocessor controller which moni- tors the leaving water temperature.

Capacity control is achieved by cycling compressor ON/OFF and slider capacity pre-set control valve. The use of slider control valve provides excellent part load capacities.

On multiple compressor units, capacity is controlled by a combination of slider capacity control valve and compressor staging. For such optional stepped load shedding, please see the following table:

SEMI-HERMETIC COMPACT TWIN SCREW COMPRESSORS

All compressors are compact semi-hermetic twin screw of the high capacity and efficiency due to its perfect profile form ratio 5:6. Simple and robust construction with slider control valve for capacity unloading, suction/discharge shut-off valves, check valve in discharge gas outlet, oil sight glass, oil fill/drain service valve, directly flanged-on three stage oil separator with long-life fine filter 10 microns mesh size, robust axial bearings in tandem configuration, suction gas filter, internal pressure relief valve and manual lock-out electronic protection system for thermal motor winding temperature, phase reversal, discharge gas temperature protection controls.

CONDENSER COILS

W-configuration condenser coils are corrugated fin and tube type, constructed of seamless 3/8" dia. & 0.014" (0.35 mm) thick copper tubes, mechanically bonded to aluminum fins for maximum heat transfer efficiency. As an option, copper fins or acrylic coated aluminum fins or other coated coils may be provided. The fins have full self spacing collars which completely cover each tube. The staggered tube design improve the thermal efficiency. End plates support sheets are 14 gauge galvanized steel, formed to provide structural strength. Each coil is pressure tested in the factory at not less than 450 psi air pressure.

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COMPACT DESIGN SHELL AND TUBE WATER COOLERS

The DX shell & tube cooler with removable ‘U’ shaped bundled tubes are made of internally grooved copper tubes expanded into a heavy steel tubular sheets.

The chiller cooler & baffles are constructed of steel and brass respectively. The coolers are insulated with heavy closed cellular foam insulation (3/4" thick). All chiller barrels are fitted with vent, drain connection and victaulic water pipe connection as standard.

MICROPROCESSOR CONTROLLER

Sequence of operation

The following describes the sequence of operation for a two screw compressor chiller unit. Operation is similar for a one or four compressor unit.

For initial start-up, the following conditions must be met:

•    All power supplied to the unit shall be energized for 12 hours.

•    Control power switch on for at least 5 minutes.

•    All safety conditions satisfied.

•    Press ESC on the microcomputer keypad.

•    Chilled water pump running and chilled water flow switch contact closed.

•    Customer interlock contact closed, if any.

TROUBLESHOOTING GUIDE

1)    No LED display lit or erratic display behavior

a)    Check serial cable integrity.

b)    Check serial cable connections on both the User Interface Board and the Main Board.

c)    Check correct and tight insertion of jumpers JU1 and JU2 on the Main Board.

d)    Check correct and tight insertion of jumpers TU1 and TD1 on the User Interface Board and on the last board of the network.

2)    Controller does not respond to keypad

a)    Check serial cable integrity.

b)    Check serial cable connections on both the User Interface Board and the Main Board.

c)    Check correct and tight insertion of jumpers TU1 and TD1 on the User Interface Board, main and/or auxiliary board.

d)    Check dip switches and integrity on the User Interface Board.

3)    Several analog values reading incorrectly

a)    Check correct and tight connection of the probes to the board.

b)    Check the probe cable: test for short-circuit.

c)    The pressure transducer probe is a 4-20mA transmitter check the polarity of the connection on the Board.

d)    Check if the power supply voltage is into the specified limits: 24Vac +/- 10%.

e)    The temperature probe is a PTC sensor disconnect it from the board and measure its resistance that is 1000 ohm at 250C or 1200 ohm at 500C.

4)    Digital input reading incorrectly

a)    Check if the auxiliary 220 Vac voltage is present in the electrical box.

b)    Check if the AC input on the Board is correctly connected to one of the 220 Vac terminals in the electrical box.

c)    Check if A1/A14 inputs are correctly connected with respect to the cabling diagram of the electrical box.

5)    No LCD display lit or erratic display behavior

a)    Check serial cable integrity.

b)    Check serial cable connections on both the User Interface Board and the Main Board.

c)    Check correct and tight insertion of jumpers JU1 and JU2 on the Main Board.

d)    Check correct and tight insertion of jumpers TU1 and TD1 on the User Interface Board, main and/or auxiliary board.

e)    Adjust display intensity by rotating trimmer RV1 counter-clockwise (from the back side of the board).

6)    No LED H1 blinking light on NG3 Board

a)    Check power supply cable an connection.

b)    Check if the power supply voltage is into the specified limits: 24Vac +/- 10%.

c)    Check for fuse F1,  replace with 1AT/250V if blown.

7)    No display of leds on User Interface Board

a)    Check serial cable integrity.

b)    Check serial cable connections on both the User Interface Board and the Main Board.

c)    Check correct and tight insertion of jumpers JU1 and JU2 on the Main Board.

d)    Check correct and tight insertion of jumpers TU1 and TD1 on the User Interface Board, main and/or auxiliary board.

8)    Auxilliary board not responding to commands

a)    Check if LED H1 on Auxilliary board is blinking , if not go to point (6).

b)    Check serial cable integrity.

c)    Check serial cable connections on both the Main and the Auxilliary boards.

d)    Check that jumpers JU1 and JU2 on the Auxilliary boards are not installed.

e)    Check correct and tight insertion of jumpers TU1 and TD1 on the User Interface Board, main and/or auxiliary board.

9)    Analog Outputs not responding

a)    Check Analog Output cables integrity (for short-circuit).

b)    Check Analog Output cabling and connections.

c)    Check if the power supply voltage is into the specified limits: 24VAC +/- 10%.

d)    Check the fuse F1, replace with 1AT/250V if blown.

10)    Digital Outputs not responding

a)    Check Digital Output cables integrity (no short-circuit, no open-circuit).

b)    Check digits Output cabling and connections.

c)    Check if the power supply voltage is into the specified limits: 24VAC +/- 10%.

d)    Check the fuse F1, replace with 1AT/250V if blown.

11)    Serial Communication with Remote Monitoring Control not Functioning

a)    Check the serial cable connected on plug-in board IS-485 mounted on the Main Board.

b)    Check if the plug-in board is correctly mounted on the Main Board.

c)    Check if jumpers X5 and X6 on the plug-in board IS-485 are correctly installed.

d)    Check if jumpers X17 and X18 on the GATEWAY board are correctly installed.


 
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