21
Main Power Termination Point
The connection point in the power section for customer
three phase power.
• 1TB1 Main terminal block (standard).
• 1S1 Line voltage non-fused disconnect switch -optional.
• Circuit breaker or shunt trip circuit breaker - optional.
Circuit Breakers and Fuses
Circuit breakers and fuses provide the branch circuit
protection identified.
• 1CB2 Line voltage transformer circuit breaker
• Circuit breaker provides branch circuit protection to 1T5
primary winding.
• 1F1, 1F2 Line voltage transformer fuses
• 1F3 Phase voltage transformer fuse
• 1F4, 1F5, 1F6 Refrigerant and absorber solution pump
motor fuses.
• 1F7, 1F8, 1F9 High and low temperature solution pump
motor fuses
• 1F10, 1F11, 1F12 Burner fan motor fuses
(ABDA only)
Relays
The following relays are utilized to isolate the starter panel
signals from low voltage control panel module input
signals.
• 1K1- Refrigerant pump abnormal relay.
• 1K2- High temperature solution pump abnormal relay.
Transformers
Transformers are utilized to reduce voltage levels. Some
are used to distribute power and others for module input
signals. The various transformers are identified below.
1T1, 1T2, 1T3 Phase Current Transformers
Current transformers are used to sense the 3 phase current
draw of the total system. The output of each current
transformer is input to the 1U1 starter module. Current
transformers are polarity sensitive. Typically, there is a
marking ”dot” on one side and the secondary wires are
black and white. The installation of the transformers must
be with the markings all facing the same direction in
reference to the current flow through the primary wiring.
The current transformer outputs are input to the starter
module, which monitors current.
Total Motor Current Monitoring
Current transformers are used to monitor total unit
currents. See Table 3 to select CT Rating. In many cases
more than one selection is possible:
1. Locate unit RLA in left column.
2. Determine the Current Transformer (CT) Meter Scale
[Rated Primary Current of Current Transformer (CT) /
Number of Primary Turns] located in right
3. Determine the Current Transformer (CT) Factor = (Actual
Motor RLA / Current Transformer (CT) Meter Scale) x
100%
4. In this case the Rated Primary Current of the Current
Transformer (CT) should be picked to be greater than
Actual Motor RLA x Number of Primary Turns. The
Current Transformer (CT) Factor must be 66% or greater
but not more than 100%.
5. From the calculated Current Transformer (CT) Factor the
Motor Overload settings can be found in Table 4.
Table 3. Current transformer selection table for single CT and phase
systems
5.6 - 8.3A (50A with Six 50A/6 =
8.3A Passes Through 8.333A
Core)
6.7 - 10.0A (50A with 50A/5 =
10A Five Passes 10A
Through Core)
8.4 - 50A/4 =
12.5A
11.2 - 50A/3 =
16.6A 16.67A
16.7 - 50A/2 =
25A 25A
25 - 75A/2 =
37.5A 37.5A
33.4 - 50A 50A
50A
50 - 75A 75A 75A
67 - 100A 100A
100A
100 - 150A 150A
150A
134 - 200A 200A
200A
Unit
RLA
CT Rating
(Assumes Single
Pass through CT
Core Unless Noted
Otherwise)
CT Meter
Scale
Value
12.5A (50A with
Five Passes
Through Core)
16.6A (50A with
Three Passes
Through Core)
25.0A (50A with
Two Passes
Through Core)
37.5A (75A with
Two Passes
Through Core)
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