Delta MCS-1800 Specifications download pdf (Page 26)

DELTA MCS-1800 3U Power Shelf

Installation, Operations and

Maintenance Manual

8-1

8 System Alarms and Troubleshooting

8.1 AC Fail Voltage Alarm Description

8.1.1 Description

If the ALU detects an input AC voltage below 50 VAC, the ALU sends an AC Fail alarm signal and

activates the dry contact. The AC Fail LED on the ALU panel lights up. When AC voltage is restored to the

nominal input voltage, the ALU extinguishes the AC Fail LED, and returns the contact to the normally closed

position.

8.1.2 Troubleshooting

The AC Fail alarm is normally caused by a commercial AC interruption due to a storm or maintenance.

If commercial AC is detected at the AC panel, check the rectifier input breakers in the AC panel for a tripped or

failed breaker.

Warning: The ALU senses the AC line through the AC Input terminal. If this connection is missing, the

system generates an AC Fail alarm.

8.2 High Voltage Shutdown Alarm

8.2.1 Description

When the ALU detects the output DC voltage exceeding the HVSD threshold setting, the ALU sends an

HVSD alarm signal and activates the dry contact. The ALU lights the HVSD LED located on the ALU panel

and shuts down each rectifier. At this point, the system is running on reserve batteries. When the DC voltage

falls below the HVSD threshold voltage, and push the HVSD RST Button, then the system recovers. The ALU

extinguishes the HVSD LED, returns the rectifiers to service, and closes the normally closed set of contacts.

8.2.2 Troubleshooting

High voltage shutdown occurs when the output voltage exceeds the HVSD threshold. This can be caused

by a rectifier failure, the system equalize voltage exceeding the HVSD threshold, or temperature compensation

exceeding the HVSD threshold setting.

1. Restart the rectifiers by resetting the HVSD RST button located on the ALU.

2. Verify the output voltage of each rectifier in both float and equalize.

3. Verify that the equalize voltage setting does not exceed the HVSD threshold setting.

4. Verify the temperature compensation voltage setting. Ensure that Temp Comp does not exceed the

HVSD threshold setting when operating in cold temperatures.

8.3 High Voltage Alarm Description

8.3.1 Description

The High Voltage alarm (HV) is a minor alarm activated when the DC output voltage exceeds the HV

threshold setting. When the system voltage exceeds the HV setting value, the ALU sends the HV alarm signal,

lights the HV LED located on the ALU panel, and activates the HV alarm contact. The rectifiers remain on

line during this minor alarm condition. When the system voltage decreases below the threshold setting, the

ALU extinguishes the HV LED and deactivates the HV alarm contact.

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Delta MCS-1800 Specifications Page 26