JOHNSON CONTROLS
15
FORM 160.00-O10
ISSUE DATE: 8/24/2020
2
SECTION 2 - SAFETY SHUTDOWNS
period (150 seconds for centrifugal chillers or
shorter for those chillers that contain the optional
“Quick Start” feature).
• The message “VSD Shutdown - Requesting Fault
Data”...will be displayed when the Control Center
is requesting the fault data from the OSCD.
• The OSCD Logic Board will send a shutdown
code via the communications link to the Control
Center. The Micro Board will interpret the shut-
down code and display a shutdown message on
the display of the Control Center.
After the coastdown period has timed out, the chiller
may be restarted if the shutdown is no longer active,
and the CLEAR FAULT key is pressed
TABLE 2 -
SAFETY SHUTDOWNS MESSAGE
MESSAGE
DESCRIPTION
VSD – DC BUS LOCKOUT –
DO NOT CYCLE POWER
When the unit is stopped in a mode where no command exists to energize the DC bus,
the DC bus voltage is monitored and checked against a threshold level of 100 VDC every
five minutes. If the DC bus voltage is higher than the threshold value, this shutdown
is generated. When the condition clears and the VSD input modules are tested and
determined acceptable the chiller can be started.
VSD – DC BUS PRE-
REGULATION LOCKOUT
If the unit fails to complete pre-regulation (due to VSD – DC BUS PRE-REGULATION
fault), it shall have to repeat pre-charge in order to attempt another pre-regulation. The
VSD shall wait 10 seconds before clearing the DC bus voltage pre-regulation fault and
allowing another pre- charge to start. The unit’s fan(s) and water pump(s) shall remain
energized during this wait time. The VSD shall allow up to three consecutive pre-
regulation-related faults (i.e. VSD-DC BUS PRE-REGULATION) to occur. After the third
consecutive fault, this shutdown is generated.
VSD – GROUND FAULT
This message is generated when the sum of the 3 phases of instantaneous input current
values are greater than the shutdown value for a period of 1 second for the given model
of drive listed below.
DRIVE MODEL
GROUND CURRENT SHUTDOWN VALUE
1100/1300
200 Amps
VSD – HIGH PHASE A INPUT
BASEPLATE TEMPERATURE
This shutdown occurred because the Input Baseplate Temperature exceeded the
shutdown value for the given model of drive listed below. After the unit trips, the VSD
fan(s) and water pump(s) shall remain energized for 2 minutes after the fault occurred.
DRIVE MODEL
HIGH PHASE A INPUT BASEPLATE
TEMPERATURE SHUTDOWN VALUE
1100
170°F (76.6°C)
1300
150°F (65.5°C)
VSD – HIGH PHASE B INPUT
BASEPLATE TEMPERATURE
See “VSD – HIGH PHASE A INPUT BASEPLATE TEMPERATURE” message preceding.
General Information
The Shutdowns are organized in alphabetical order
based on the OptiView™ Control Center messages.
Whenever a Safety Shutdown is generated by the
OSCD, a series of events will occur.
• If the chiller is not running at the time of the shut-
down, the OSCD Logic Board will not turn on the
gate drivers.
• The K3 relay on the OSCD logic board will de-
energize to indicate to the Control Center that the
OSCD has shutdown. The K3 relay will remain
de-energized until the cause of the shutdown has
been corrected.
• If the chiller is running at the time of the shut-
down, the Control Center will start a coastdown
