Harris Atlas DVL400, Technical Manual

Page: 142 / 180

4-42 888-2473-001 2/25/03
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation ATLAS Series™
when the panel is in Local mode or is changed from Remote to Local. Press-
ing Pump B will change K4 to the opposite position of that shown and will
light the Pump B Pre-Set LED H8. It will select Pump B only when the panel
is in Local mode or is changed from Remote to Local.
4.6.4.3 Control Voltage Power Supply
Two of the three ac phases are taken through fuses F1 and F2 to stepdown
transformer T1. This supplies 24Vac for the coils on the motor contactors K1-K4.
The 24Vac is also rectified for a +34Vdc output which is used for most of the status
LEDs and the small relays on the PC board. The Power LED H1 will be lit if the
+34 Vdc is present.
The +34Vdc is also supplied, via X2-2, to the transmitter pump select relays on the
Atlas External I/O board. It is fused in the transmitter at 5A by fuse F1. There is a
green LED on the External I/O board that will be illuminated if the +34Vdc is
present.
4.6.4.4 Control Description
The following will describe the operation of the control panel based on the normal
Remote operation mode. Then fault modes will be discussed as changes to this
normal operational mode. The control panel will be assumed to be Remote mode, ac
power is applied to the control panel with all system isolator switches closed.
NOTE:
When the transmitter is shut off it will allow the cooling system to run for an
additional 5 minutes before shutting it off.
4.6.4.4.1 Latching Relay K3
In remote mode, K3 is in the position shown. This lights the Remote status LED H2
which is physically located directly above the Remote button on the front panel.
This also sends a Remote Selected Status signal to the transmitter via X2 pin 11.
This is optically coupled into the transmitter control system for status display on the
GUI.