1. STAR-DELTA RELAYS M STAR-DELTA BOX FAN 3 K3 K1 K2 N L1 L2 L3 35 36 3738 39 40
STAR-DELTA BOX 45 K3 5 K1 K2 1 2 3 N L1 L2 L3

2. STAR-DELTA MODE OPERATION5 42
From #6 of control box;
conditions to be energised:
1) auxiliary circuit ‘ON’
2) No lock out of control box
3) min air P.switch at
stand-by position at beginning
4) max air P.switch closed
5) limit controls closed
6) fuel selected
gas side:
7) leakage control OK
8) min gas P.switch closed K1 K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N

3. STAR-DELTA MODE OPERATION5 42 K1 K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N

4. STAR-DELTA MODE OPERATION5 42 K1 K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N

5. STAR-DELTA MODE OPERATION5 42
The fan motor turns by slow speed,
as supplied at star voltage K1 K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N

6. STAR-DELTA MODE OPERATION5 42 K1
Few seconds later two contacts of
the relay K4 (it’s a slow operating
relay) change their position K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N

7. STAR-DELTA MODE OPERATION5 42 K1
Few seconds later two contacts of
the relay K4 (it’s a slow operating
relay) change their position K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N

8. STAR-DELTA MODE OPERATION5 42 K1
Few seconds later two contacts of
the relay K4 (it’s a slow operating
relay) change their position K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N

9. STAR-DELTA MODE OPERATION5 42
The fan motor turns by high speed,
as supplied at delta voltage K1 K1 K2 K1 = = 45 K4 K3 K2 K4 K1 K2 K3 N