4 Fault Isolation
4.13 Power System Indicators
R688 HPM High-Performance Process Manager Service 383
December 2020 Honeywell
DC Out indicator
If a DC Out LED is off, ac line power has been lost (check the AC In LED) or the Power Supply
Module has failed. If the Power System is nonredundant, or if both DC Out LEDs are off, the HPM has
lost 24 Vdc. The CMOS backup system maintains power to the CMOS memory, so subsystem programs
are not lost. See the Battery LED description below. A set of annunciator contacts, which are illustrated
in Figure 187, open when these conditions occur.
Battery indicator
If the Battery LED is off and the Charge LED is on, the 48 Volt Battery switch is in the off position
or the 48 V Battery Backup system has failed. A set of annunciator contacts, which are illustrated in
Figure 187, open when these conditions occur. If the Power System does not have the battery pack
option, the Battery LED will normally be on, and the Charge LED will normally be on.
Fan/Temp indicator
If the Fan/Temp LED is off, the fan in the Power Supply Module has failed or the temperature of the
HPM has exceeded a safe value. An annunciator contact, discussed below, is activated by any of the five
conditions described below.
AC In indicator
If the AC In LED is off, ac power to the HPM has been lost or the switch on the Power Supply Module
is off. Backup systems, if operating, are maintaining the unit. Check the DC Out and Battery indicators
to determine the state of the system. Some installations may have the Power Supply Modules connected
to the separate ac power sources to minimize outage caused by a power loss. Annunciator contacts,
illustrated in Figure 187, signifying power loss from either supply, are activated independently.
Charging indicator
When the Charging LED is off, the charging circuit that maintains the optional 48 V Battery Backup
system has failed. Check the batteries, their corresponding connections, and the charging circuits in the
Power Supply Module (s). An annunciator contact output, illustrated in Figure 187, is activated by this
condition.
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