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FORM 160.54-M1
ISSUE DATE: 10/25/2019
SECTION 18 - OIL PUMP VARIABLE SPEED DRIVE
On Style D (and later) chillers, the oil pump is driven
by a Variable Speed Drive (VSD) (Refer to Variable
Speed Oil Pump Drive (Form 160.52-M2) for details of
this device). In normal operation, the oil pump speed is
automatically controlled to maintain a desired oil pres-
sure. The speed can be manually controlled with the
keypad keys using the OIL SUMP screen with SER-
VICE access level.
On those chillers equipped with the oil pump VSD,
the VSD operation must be ENABLED by placing
microboard program switch SW1-2 in the ON posi-
tion. Chillers not equipped with the oil pump VSD
must have this operation DISABLED by placing SW1-
2 in the OFF position. Refer to microboard program
switches.
The programming of the setpoints referred to below is
performed on the OIL SUMP Screen using instructions
in SECTION 33 - SYSTEM CALIBRATION, SERVICE
SETPOINTS, AND RESET PROCEDURES of this
manual. These setpoints should not be programmed
by anyone other than a qualified Service technician.
Variable speed oil pump chillers are not equipped
with the Liquid Line Solenoid Valve (2SOL), or High
Speed Thrust Solenoid Valve (4SOL). Therefore, when
Oil Pump VSD operation is ENABLED with Program
Switch SW1-2, the Program is configured to operate
the chiller without these solenoid valves. Operation Se-
quence Timing Diagrams in Figure 8 on page 29 and
Figure 9 on page 30 depict chiller operation with
the Oil Pump VSD enabled or disabled. Also, when
equipped with the Oil Pump VSD, the microboard, un-
der Program control, controls the Oil Heater to main-
tain a specific oil temperature as described in the "Oil
Heater" section below.
AUTOMATIC OPERATION
Under program control, a speed command signal from
the microboard controls the oil pump speed by varying
the VSD output frequency. The speed command is in
the form of a Pulse Width Modulation (PWM) Signal
as explained below. During the System Pre-lube period
and the first 15 seconds of System run, the Program
operates the Oil Pump VSD over the range of 25Hz to
60Hz to maintain the oil pressure to the target value
of 45 psid. For the remainder of System run and the
Coastdown period, it operates it over the same frequen-
cy range to maintain the pressure to the programmed
oil pressure setpoint.
JOHNSON CONTROLS
When the chiller is started, 13 seconds after the Sys-
tem Pre-lube is initiated, the microboard (J20-3)
starts the oil pump by driving the EN (enable) input
of the oil pump VSD to a Logic Low level (less than
1 VDC). The microboard (J20-1) then applies a speed
command signal to the PWM input of the VSD that
ramps the VSD output frequency from 25 Hz (45 Hz
on all P compressors; 45Hz on other compressor ap-
plications equipped with Flash memory card version
C.MLM.01.05.xxx (and later)) to whatever frequency
is required (up to a maximum of 60 Hz) to achieve the
Target Oil Pressure.
(If equipped with flash memory card version
C.MLM.01.08.xxx (and later), it is held at 45Hz for
eight seconds before releasing to normal control).The
target oil pressure is fixed at 45 psid. The speed com-
mand is displayed on the OIL SUMP screen as OIL
PUMP DRIVE COMMAND FREQUENCY = XXHz.
The speed command to the VSD is modulated as re-
quired to maintain the 45 psid target oil pressure for
the remainder of system pre-lube and the first 15 sec-
onds of system run. While this target is in effect, the
OIL SUMP screen displays as TARGET OIL PRES-
SURE = 45 psid. The time remaining that the target oil
pressure is in effect is displayed as a countdown timer
in the message PULLDOWN TIME REMAINING =
XX SEC. After the compressor has been running for 15
seconds, VSD speed is controlled to maintain the pro-
grammed oil pressure setpoint (20 to 45 psid), which is
displayed on the OIL SUMP screen as SETPOINT OIL
PRESSURE = XX psid.
During oil pump operation, the following minimum
and maximum oil pressures are allowed:
1. During automatic operation, if the following con-
ditions occur, a safety shutdown is performed and
OIL - VARIABLE SPEED PUMP - PRESSURE
SETPOINT NOT ACHIEVED is displayed. These
conditions are not checked in MANUAL opera-
tion. With software version C.OPT.01.18.307 (or
later), when the refrigerant selection (Microboard
031-02430-000/001 SW1-1) is set to R-22, these
conditions are not checked.
a. If the oil pressure is less than 35 psid
JCI COMPANY CONFIDENTIAL
(<25.0 psid for P compressors equipped
with software version C.MLM.01.10A.or
C.OPT.01.10A) for five continuous seconds
during the last 10 seconds of system pre-lube
or during the first 15 seconds of system run.
18
171
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