Product Manual

6
2.5.1 LOAD SHED SEQUENCE OF OPERATION
When configured for full functionality, six loads are organized into
four priority groups. Priority 1 (A/C 1) and the associated general use
contactor (Load 1) is the highest priority and is usually the first load(s)
reconnected (except in fast load shed mode). Priority 4 (Load 4) is the
lowest priority and is usually the last load reconnected (except in fast
load shed mode). The priority groups are as follows:
Priority Group 1
• A/C 1 and Load 1
Priority Group 2
• A/C 2 and Load 2
Priority Group 3
• Load 3
Priority Group 4
• Load 4
Since A/C is typically considered the most important, it is hardwired as
the two highest priority levels (A/C 1, A/C 2). Two other loads that may
be considered of equivalent importance are wired to the associated
general use contactors (Load 1, Load 2). Loads of lesser importance
are wired to the remaining contactors (Load 3, Load 4).
If the OPCB is fully functional and managing six connected loads,
and an event occurs which causes a load to increase beyond the
capacity of the generator, the OPCB identifies an overload condition
and instantly sheds all loads. After five minutes elapses, the OPCB
reconnects the loads associated with Priority Group 1 (A/C 1, Load 1),
and then reconnects the remaining loads at fifteen second intervals.
If the OPCB sees another overload while it is reconnecting loads, the
offending load is shed and locked out for 30 minutes. The next load
in the sequence is then reconnected. This process continues until all
loads have tried to reconnect (Figure 2.2).
Figure 2.2 — Standard Load Shed
Overload Condition - All Loads Shed
5 Minutes Elapses - Priority Group 1 Reconnected
15 Seconds Elapses - Priority Group 2 Reconnected
15 Seconds Elapses - Priority Group 3 Reconnected
15 Seconds Elapses - Priority Group 4 Reconnected
2.6 CONNECTION OF POWER
SUPPLY FOR CONTACTORS
The Overload Prevention Control Board (OPCB) can be powered from
either a 24 Vac or 120 Vac power supply. The 24 Vac supply is from
a class 2 transformer that can be purchased from the manufacturer.
Mounting holes are provided in the enclosure subplate for mounting of
the transformer. The 120 Vac supply is fused at 5 amps and is factory
connected to OPCB terminals labeled "T1 and "Neutral".
2.6.1 24 VAC SUPPLY
Transformer connection are made as shown in Figure 2.3.
• Blue wire - OPCB "LOAD SUPPLY 1" terminal
• Black wire - OPCB "T1" terminal
• White wire - OPCB "NEUTRAL" terminal
• Yellow wire - OPCB "LOAD SUPPLY 2" terminal
Installation
0 Ground
194 +12V
23 Transfer
T1
NEUTRAL
A/C 1
24V
A/C 2
24V
LOAD 1
LOAD 2
LOAD 3
LOAD
4
A/C 1 & LOAD 1
LOAD
SUPPLY
LOAD
SUPPLY
1
2
1
2
2
2
2
1
1
1
1A MAX
1A MAX
1A MAX
1A MAX
A/C 2 & LOAD 2
LOAD 3
LOAD 4
Blue
Black
White
Yellow
Factory
wiring
Transformer
leads
Field installed
Existing
wiring
Figure 2.3 — 24 Vac Supply Connections