Specifications

EXTERNALLY POWERED DEMAND LIMIT (4 to 20 mA
Controlled) — In this example, the 4 to 20 mA Demand Limit
will be configured and the 20 mA demand limit percentage
will be set to 50%. See Table 30 and Fig. 11.
DEMAND LIMIT (CCN Loadshed Controlled) — In this
example, the CCN Loadshed Demand Limit will be config-
ured. The loadshed group will be set to 1, demand delta will
be set to 40% and the maximum loadshed time will be set to
90 minutes. See Table 31.
The Loadshed Group number is established by the CCN
system designer. The PIC (product integrated control) will
respond to a Redline command from the Loadshed control.
When the Redline command is received, the current stage of
capacity is set to the maximum stages available. Should the
loadshed control send a Loadshed command, the PIC will
reduce the current stages by the value entered for Loadshed
Demand delta. For the above example the Loadshed De-
mand delta is 40%. If the chiller is operating at 80% of total
capacity when a Redline command is received, the maxi-
mum available capacity is set to 80%. When a Loadshed com-
mand is received, the chiller capacity will be reduced by 40%.
The chiller can now operate at a total capacity of no more
than 48% [80% − (80% x 40%)] until a Cancel Redline or
Cancel Loadshed command is received. The control will dis-
able the Redline/Loadshed command if no Cancel command
has been received within the configured maximum loadshed
time limit.
Table 29 — Setting Switch-Controlled Demand Limit
KEYPAD
ENTRY
DISPLAY
RESPONSE
COMMENTS
COOLING RESET
TYPE 1
DEMAND LIMIT Scroll down to this
point
Demand Limit at 20 mA
0.0%
Demand Limit Select
0
Demand Limit Select
1
Two step switch
configured
COOLING
DEMAND LIMIT Scroll down to this
point
Demand Switch 1 Setpoint
80.0%
Demand Switch 1 Setpoint
75.0
Demand Switch 2 Setpoint
50.0%
Demand Switch 2 Setpoint
40.0%
Configuration
complete
Table 30 — Setting Demand Limit
(4 to 20 mA Controlled;
2 to 10 vdc With 500-Ohm Resistor)
KEYPAD
ENTRY
DISPLAY
RESPONSE
COMMENTS
COOLING RESET
TYPE 1
DEMAND LIMIT Scroll down to this
point
Demand Limit at 20 mA
0.0%
Demand Limit at 20 mA
50.0%
Demand Limit Select
0
Demand Limit Select
2
4-20 mA control
configured
Table 31 — Setting Demand Limit
(CCN Loadshed Controlled)
KEYPAD
ENTRY
DISPLAY
RESPONSE
COMMENTS
COOLING RESET TYPE
1
DEMAND LIMIT Scroll down to
this point
Demand Limit at 20 mA
0.0%
Demand Limit Select
0
Demand Limit Select
3
CCN Loadshed
control configured
Loadshed Group Number
0
Loadshed Group Number
1
Loadshed Demand Delta
0
Loadshed Demand Delta
40%
Maximum Loadshed Time
60 min
Maximum Loadshed Time
90 min
Configuration
complete
50% CAPACITY AT 20 mA
75% CAPACITY AT 12 mA
100% CAPACITY AT 4 mA
0 (0)
2 (1)
4 (2)
6 (3)
8 (4)
10 (5)
12 (6)
14 (7)
16 (8) 18 (9)
20 (10)
DEMAND LIMIT SIGNAL – 4 - 20 mA INPUT (VOLTS DC)
100
80
60
40
20
0
MAX. ALLOWABLE LOAD (%)
Fig. 11—4to20mADemand Limiting
42