JOHNSON CONTROLS
97
SECTION 6 - OPERATION
FORM 201.30-ICOM1 (519)
ISSUE DATE: 05/22/2019
6
TABLE 32 -
UNIT SAFETIES (FAULTS)
MESSAGE
DESCRIPTION
UNIT YYYYYYY
DC BUS VOLTAGE
IMBALANCE
Software-Initiated Fault -
The voltage magnitude of each half of the DC bus shall remain within
+/- 100 VDC of the total DC bus voltage divided by two. If the magnitude exceeds the +/- 100
volt window the unit shall initiate a shutdown. This safety will lock out on the first occurrence. The
VSD shutdown type is immediate. YYYYYYY will show LOCKOUT, and the system will not restart
until the operator clears the fault using the keypad.
UNIT YYYYYYY
HIGH DC BUS
VOLTAGE TRIP
Hardware-Initiated Fault -
The high DC bus over voltage trip level is determined by hardware
on the logic board, and it is designed to trip the unit if the DC bus exceeds 766 +/- 30 VDC. This
is an auto-restart safety that will lock out on the third fault in 90 minutes. The VSD shutdown type
is immediate. YYYYYYY will show FAULT to indicate a system is in a FAULT condition, and will
restart when the 120 second anti-recycle timer times out; or will show LOCKOUT, and the system
will not restart until the operator clears the fault using the keypad.
UNIT YYYYYYY
HIGH LEAVING
CONDENSER LIQUID
TEMP
This fault protects the chiller from a high pressure cutout. This situation could occur under low
flow/high head conditions or if the control setpoint values are improperly programmed. Any time
the leaving condenser liquid temperature (water or brine) increases above the programmable
cutout point, the chiller will shutdown. Restart can occur, if demand allows, when condenser
leaving liquid temperature falls 4°F (2.2 °C) below the cutout. This fault cannot cause a lockout.
The unit will be inhibited from starting if the leaving condenser liquid temp is above the cutout
plus 4°F (2.2 °C). YYYYYYY will show FAULT to indicate a system is in a FAULT condition, and
will restart when the 120 second anti-recycle timer times out.
UNIT YYYYYYY
HIGH VSD INTERNAL
AMBIENT TEMP
Software-Initiated Fault -
The VSD logic board contains a temperature sensor, which monitors
the unit’s internal ambient temperature. The magnitude of the unit’s internal temperature is
compared to a limit of 158°F (70°C). If this limit is exceeded, the unit initiates a shutdown. The
VSD cooling fan and water pump will remain energized until the internal temperature drops
below 148°F (64.4°C) at which time the unit will be allowed to restart. The VSD cooling fan and
water pump are de-energized when the internal temperature drops below 143°F (61.6°C). This
fault will not cause a lockout. The VSD shutdown type is ramped. YYYYYYY will show FAULT to
indicate a system is in a FAULT condition, and will restart when the 120 second anti-recycle timer
times out.
UNIT YYYYYYY
LOW DC BUS
VOLTAGE
Software-Initiated Fault -
The DC bus under voltage trip level is dependent on the configuration
of the VSD is as follows: Shutdown is set at 500 VDC on 460V, 60 Hz VSD, or 414 VDC on 380V
50/60Hz and 400/415V 50 Hz VSD. This is an auto-restart safety that will lock out on the third
fault in 90 minutes. The VSD shutdown type is immediate. YYYYYYY will show FAULT to indicate
a system is in a FAULT condition, and will restart when the 120 second anti-recycle timer times
out; or will show LOCKOUT, and the system will not restart until the operator clears the fault
using the keypad.
UNIT YYYYYYY
LOW LEAVING
CHILLED LIQUID
TEMP
This fault helps to protect the chiller from an evaporator freeze-up should the chilled liquid
temperature drop below the freezing point. This situation could occur under low flow conditions or
if the setpoint values are improperly programmed. Any time the leaving chilled liquid temperature
(water or brine) drops below the programmable cutout point, the chiller will fault and shut down
with a ramped shutdown. The water trip temperature is 36° F (2.2°C) or programmable for brine
from 5°F to 36°F, default 36.0° (-15°C to 2.2°C, default is 2.2°C). Restart can occur, if demand
allows, when the chilled liquid temperature rises 4°F (2.2°C) above the cutout. This fault does not
cause a lockout. YYYYYYY will show FAULT to indicate a system is in a FAULT condition, and
will restart when the 120 second anti-recycle timer times out.
UNIT YYYYYYY
MOTOR CURRENT
OVERLOAD
Hardware-Initiated Fault -
This fault compares the highest of the three phases of motor current
per compressor to the compressor’s 105% FLA ADJUST (overload) potentiometer setting. If
the current exceeds the setting continuously for 30 seconds, all compressors will shut down.
This safety will lockout a system on the first occurrence. The VSD shutdown type is immediate.
YYYYYYY will show LOCKOUT, and the system will not restart until the operator clears the fault
using the keypad.
Summary of Contents for YVWA
Page 155: ...JOHNSON CONTROLS 155 NOTES...
