Table of Contents
Advertisement
Product Description
MOTOR STARTING
Two types of compressor motor starting are available:
Across-the-Line and optional Wye-Delta Open Transi-
tion Starter.
Across-the-Line starters will utilize one contactor and
one start relay per compressor. The optional Wye-Delta
starter utilizes 4 motor contactors, a transition delay
relay, a start relay, and a start-wye relay.
The Wye-Delta start allows inrush current to be limited
to approximately 33% LRA for the first 4 to 10 seconds,
with current increasing to normal running current when
the Delta connection is completed.
When the micro initiates a start signal at Relay Output
Board #1 (SYS 1) Terminal 20 or Relay Output Board
#2 (SYS 2) Terminal 20 to run a compressor, the 1CR
(SYS 1) or 2CR (SYS 2) relay is energized. The transi-
tion of the 1CR (SYS 1) or 2CR (SYS 2) relay contacts
energizes the 1S (SYS 1) or 2S (SYS 2) relay approx.
16ms later. The 1S/2S contacts in turn energize the 1M
(SYS 1) or 3M (SYS 2) motor contacts 16ms later. This
completes the "WYE" connection of the motor start.
At the same time, the normally closed 1S/2S auxiliary
interlock contact opens preventing the 2M (SYS 1) or
4M (SYS 2) motor contactors from energizing. Auxil-
iary contacts from 1M (SYS 1) or 3M (SYS 2) close,
interlocking the 1M (SYS 1) or 3M (SYS 2) contactors,
keeping them energized in parallel with 1S (SYS 1) or
2S (SYS 2).
The "WYE" connection of the motor start is enabled
for 4 to 10 seconds depending upon motor current as
sensed by the microprocessor. Normally, the transition
to Delta takes 10 seconds if current is below 125% FLA.
If motor current exceeds 125% FLA, the transition is
made to Delta as long as the WYE has been enabled for
at least 4 seconds.
After the "WYE" connection is enabled for 4 to 10
seconds, the 1TR (SYS 1) or 2TR (SYS 2) transition
delay relay is enabled by the microprocessor from Relay
Output Board #1 Terminal 8 (SYS 1) or Relay Output
Board #2 Terminal 6 (SYS 2). The 1TR (SYS 1) or 2TR
(SYS 2) contacts open, de-energizing 1S (SYS 1) or 2S
(SYS 2). 1M (SYS 1) or 3M (SYS 2) remain energizes
through interlocking contacts 1M (SYS 1) or 3M (SYS
2). Opening of the 1TR (SYS 1) or 2TR (SYS 2) con-
tacts deenergizes 1S/2S and closes the normally closed
1S (SYS 1) or 2S (SYS 2) contacts, energizing motor
JOHNSON CONTROLS
contactor 2M (SYS 1) or 4M (SYS 2), completing the
"DELTA" connection of the motor.
1 TR and 2TR are NOT "timing"
relays. These devices are simply pilot
relays identical to 1CR and 2CR.
KEYPAD CONTROLS
Display
Parameters are displayed in English (°F and PSIG) or
Metric (°C and Bars) units, and for each circuit, the
following items can be displayed:
• Return and leaving chilled liquid, and ambient tem-
perature.
• Day, date and time. Daily start/stop times. Holiday
and Manual Override status.
• Compressor operating hours and starts. Automatic
or manual lead/lag. Lead compressor identification.
• Run permissive status. No cooling load condition.
Compressor run status.
• Anti-recycle timer and anti-coincident start timer
status per compressor.
• System suction (and suction superheat), discharge,
and oil pressures and temperatures.
• Percent full load compressor motor current per phase
and average per phase. Compressor capacity control
valve input steps.
• Cutout status and setpoints for: supply fluid tempera-
ture, low suction pressure, high discharge pressure
and temperature, high oil temperature, low and high
ambient, phase rotation safety, and low leaving
liquid temperature.
• Unloading limit setpoints for high discharge pres-
sure and compressor motor current.
• Liquid pull-down rate sensitivity (0.5°F to 5°F
[0.3°C to 2.8°C] /minute in 0.1° increments).
• Status of: evaporator heater, condenser fans, load
and unload timers, chilled water pump.
• "Out of range" message.
• Up to 6 fault shut down conditions.
The standard display language is English, with 4 other
languages available.
FORM 201.18-NM7
23
Advertisement
Table of Contents
