APC ACRA100 Installation Manual download pdf (Page 63)

55Pumped Refrigerant System Operation and Maintenance

Troubleshooting

Problem

Possible Cause Corrective Action

Display interface not

operational, but

equipment operates

• Display interface

not connected

properly

• Verify that the display interface cable is connected properly.

Alarms do not show up

on monitoring equipment

(Customer Output

Contact)

• External

monitoring

equipment is not

receiving power or

is not functioning

properly

• Confirm that power, if required, is being supplied to the external

equipment.

• If the RDU is providing power to the external equipment, verify that the

external equipment is <

50 mA.

• Test the external equipment by bypassing the customer output contact.

Equipment does not shut

down on command

• Drive voltage • Verify that there is a drive voltage entering the input of the RDU. You

may use the +12 V or +24 V. You must also use the ground.

No communication with

building management

system (BMS) port

• Improper

connection

• Confirm that the RDU is connected to the BMS port and not to the

Control port.

• Make sure that the wire polarity is correct. Using a DC voltmeter, test the

signal with no transmissions in progress. Expect the voltage at pin 2 to

be greater than at pin 1 by at least 200 mV. Measure the RDU with the

cable disconnected, and then measure it again with the cable connected.

If the signal is less than 200 mV, the RDU may be reverse-wired.

• Make sure every CM has either two sets of wires on the connector or one

set of wires and a terminating resistor of 100 to 120 ohms.

Cooling modules are not

communicating with the

RDU

• A-Link failure • Verify that the first and last cooling modules have one cable and a

terminator.

• Verify that every other cooling module has two cables.

• Confirm that the A-Link cables are connected to the A-Link ports and

that a network cable is connected to the network port.

• Verify that the number of cooling modules in the cooling group matches

the group number setting.

Equipment does not shut

down on command

• Drive voltage • Verify that there is a drive voltage entering the input of the cooling unit.

You may use the available +12 V or +24 V. You must also use the

ground.

No communication with

building management

system (BMS) port

• Improper

connection

• Confirm that the RDU is connected to the BMS port and not to the

Control port.

• Make sure that the wire polarity is correct. Using a DC voltmeter, test the

signal with no transmissions in progress. Expect the voltage at pin 2 to

be greater than at pin 1 by at least 200 mV. Measure the RDU with the

cable disconnected, and then measure it again with the cable connected.

If the signal is less than 200 mV, the RDU may be reverse-wired.

• Make sure that every CM has either two sets of wires on the connector or

one set of wires and a terminating resistor of 100 to 120 ohms.

CMs are not

communicating with

each other

• A-Link failure • Verify that the first and last CMs have one cable and a terminator.

• Verify that every other cooling module has two cables.

• Confirm that the A-Link cables are connected to the A-Link ports and

that a network cable is connected to the network port.

• Verify that the number of CMs in the cooling group matches the group

number setting.

Output air is 17° C

(62° F) and CM fans are

running at a very high

rate of speed.

•Upper or lower

supply air sensor

• Either the upper or lower supply air temperature sensor has a fault.

Verify that both supply air temperature sensors are installed and working

properly.

1 2 ... 58 59 60 61 62 63 64 65 66 67 68

Comments to this Manuals

No comments

APC ACRA100 Installation Manual Page 63

Comments to this Manuals

Related products and manuals for Hardware cooling accessories APC ACRA100