Emerson Vilter VilTech, Руководство по эксплуатации и обслуживанию

Страница: 136 / 174

136
Addendum for Pump Down Program for VILTech
The VILTech needs to be setup for Remote operation, Auto Start/Stop enabled, and Suction
Pressure control. The Process Temperature control is not an option for capacity control and
is used instead to control the Chiller Liquid Valve.
When the controller is On-Line, the Remote Start/Stop input energizes, and the Process Tem-
perature input is above the High Temperature Cut-In setpoint; the Chiller Liquid Valve will be
opened. Then when the Chiller Liquid Valve is open and the Suction Pressure rises above the
Cut-In setpoint, the compressor starts.
Note: that if the Process Temperature is not above the High Temperature setpoint or if the
compressor is not On-Line, the Chiller Liquid Valve will not be opened and the compressor
will not start even if the Suction Pressure is above the Cut-In setpoint.
As long as the Process Temperature remains above the Low Temperature setpoint, the com-
pressor will load, unload, cut-out, and cut-in normally based on the Suction Pressure control
setpoints. If the Process Temperature falls below a Low Temperature setpoint, the Chiller
Liquid Valve will be closed and the compressor should pump down and shutoff normally when
the Suction Pressure falls below the Cut-Out setpoint. But if the Remote Start/Stop input is de-
energized, the Liquid Valve will be closed right away but the compressor will be allowed to
pump down and shutoff normally when the Suction Pressure falls below the Cut-Out setpoint.
Other operations are still allowed like Automatic operation is permitted when using the AUTO
button on the panel. In this case, operation is the same except that the Remote Start/Stop input
is ignored. Manual operation is permitted when using the MAN button on the panel. In this
case, the compressor starts and the Chiller Liquid Valve opens and closes normally with
temperature but none of the time delays, cut-in, cut-out, or automatic capacity controls are
used. Manual capacity control is available.
A user-programmable time delay will be started anytime the compressor starts to prevent the
compressor from stopping due to the Cut-Out setpoint or a Low Suction Pressure Failure.
The default time delay is 90 seconds should be varied with each application. For example,
when using glycol, this time delay can be shortened to 5 seconds or less. High and Low
Suction Pressure alarms and failures will remain inhibited for the time delay period and when
the compressor is stopped.