York YK Service Manual

YORK INTERNATIONAL
6
AUTOMATIC SPEED CONTROL
The Micro Board controls the VSOP drive output fre-
quency by applying a Pulse Width Modulation (PWM)
speed command signal to the VSOP drive (ref Fig. 2).
The signal is applied every 0.7 seconds. Within the 0.7
second period, the duration of time that the signal is
“low” (0VDC) , determines the VSD output frequency
between 25 to 60Hz. If the signal remains “high”
(+12VDC) for the entire 0.7 second period, it is com-
manding the VSOP drive’s output frequency to 25Hz.
If the signal is low for the entire 0.7 second period, it is
commanding the VSOP drive’s output frequency to
60Hz. Frequencies between these extremes are
achieved by driving the signal low for a proportionate
amount of time within the 0.7 second period. For ex-
ample, if the signal is low for 50% (0.35 seconds) of the
0.7 second period, it would be commanding the VSOP
drive to operate at a frequency that is halfway between
25 and 60Hz, or 42.5Hz. The resolution, or smallest in-
crement of change, is 0.01 seconds. This allows the
output frequency to be changed in 0.5 Hz steps. The
formula provided in Figure 2 can be used to calculate
the output frequency for a given PWM signal.
The entire VSOP drive run time is divided into “Oil
Pressure Control Periods”. They run consecutively
and continuously; when the first one ends, the next one
begins. This repeats until the oil pump is shut down.
The duration of the periods are determined by the “OIL
PRS CTRL PERIOD SETPOINT”, programmed by
the Service Technician using instructions under “Pro-
gramming”. This setpoint is programmed in multiples
of 0.3 seconds over the range of 0.3 to 2.7 seconds, by
programming a “MULTIPLIER” value of 1 through 9.
The program multiplies this value by 0.3 to produce pe-
riods over the range of 0.3 to 2.7 seconds. This multi-
plier value also determines the magnitude of output fre-
quency correction when the error between the actual
oil pressure and the oil pressure setpoint is > ± 6 PSID).
The programmed value (1 through 9) is multiplied by
0.5Hz to provide greater frequency change to more
quickly correct the oil pressure. If the error is > ±0.5
PSID & <± 6 PSID, the output frequency is increased
or decreased 0.5Hz. At the end of each period, the ac-
tual oil pressure is compared to the programmed Oil
Pressure Setpoint and the Micro Board changes the
speed command as required per the following:
If actual oil pressure is:
a. >(setpoint + 0.5 PSID) &
<(setpoint + 6 PSID),
decrease output frequency 0.5Hz.
b. >(setpoint + 6 PSID), decrease output frequency
0.5Hz x Control Period Multiplier.
c. <(setpoint – 0.5 PSID) &
>(setpoint – 6 PSID),
increase output frequency 0.5Hz.
d. <(setpoint – 6 PSID), increase output frequency
0.5Hz x Control Period multiplier.
- 6 PSID
- .5 PSID
+ .5 PSID
+ 6 PSID
OIL PRESSURE
SETPOINT
CONDITION 'B' DECREASE OUTPUT FREQUENCY
0.5HZ x CONTROL PERIOD MULTIPLER
CONDITION 'A' DECREASE OUTPUT FREQUENCY
0.5HZ
NO CHANGE IN OUTPUT FREQUENCY
NO CHANGE IN OUTPUT FREQUENCY
CONDITION 'C' INCREASE OUTPUT FREQUENCY
0.5HZ
CONDITION 'D' INCREASE OUTPUT FREQUENCY
0.5HZ x CONTROL PERIOD MULTIPLER
VSOP DRIVE OUTPUT FREQUENCY CONTROL
ACTUAL OIL
PRESSURE
Since this EPROM version can be used on chillers that
are equipped with the VSOP drive and those that are
not, VSOP drive control must be enabled or disabled, as
appropriate, and the associated setpoints programmed
using the “Programming” procedure on page 8.
LD04651

York YK Specifications

General

Model	YK
Type	Centrifugal Chiller
Refrigerant	R-134a
Frequency	50/60 Hz
Compressor Type	Centrifugal
Application	Commercial and Industrial
Cooling Capacity Range	400 to 2, 500 tons
Full Load Efficiency	0.50 to 0.60 kW/ton
Efficiency	Varies by model (See specific model data)
Operating Temperature Range	Varies by model (See specific model data)

Summary

VSD Oil Pump General Information - Mod D Chillers

VSD Oil Pump Style Variations

Details variations in VSOP drive part numbers based on input voltage ranges.

VSD Oil Pump Drive Overview

Explains the function and components of the VSOP drive in Model "D" chillers.

Known Problems

Lists common issues encountered with early VSOP drive software and voltage disturbances.

Variable Speed Oil Pump Drive Operation - Model D Chiller

Microcomputer Control Center Operation

Describes how the Microcomputer Control Center manages oil pressure via the VSOP drive.

Automatic Speed Control

Manual Speed Control

Programming

Micro Board Changes

Standby Lubrication

Safety Shutdowns

High Oil Flow

Describes safety shutdown conditions related to high oil flow or low oil pressure.

Daytime-High Oil Flow

Specifies conditions for daytime high oil flow safety shutdown.

Oil Pump Operation After Power Failures

Explains how the oil pump operates after a power failure and system restart.

Diagnostic Software - Digital Outputs

Details manual control of VSOP drive outputs via diagnostic software.

Fault Indications From the VSOP Drive

Oil Pump Drive Status LED

Explains the meaning of the VSOP drive status LED colors and states.

VSOP Drive Okay Relay

Describes the function of the VSOP drive okay relay contacts for fault detection.

Auto Re-settable Shutdowns

Lists faults that cause auto-resetting shutdowns, like heatsink overtemp and undervoltage.

Non Auto Resettable Shutdowns

Overload

Explains overload shutdowns based on high output current over time.

Overvoltage

Details overvoltage conditions that cause VSOP drive faults and auto-restart.

Output line to line short

Describes faults caused by short circuits on the VSOP drive output.

Locked Rotor

Details faults occurring when the motor rotor is locked and does not rotate.

Troubleshooting Guide (Mod D Chillers)

Blown Input Fuses or the status LED is not lit.

Troubleshooting steps for blown fuses or an unlit status LED on the VSOP drive.

Control Center AUTOSTART, VSOP LED flashing RED.

Addresses issues when control center shows AUTOSTART and VSOP LED is flashing red.

Control Center AUTOSTART, VSOP LED constant RED.

Troubleshoots control center AUTOSTART with VSOP LED constantly red.

VSOP Drive Not Starting, Status LED Constant RED.

Diagnoses VSOP drive startup failure with a constant red LED.

Oil Pressure Regulation and Motor Rotation Issues

Oil Pressure Not Regulating to Setpoint

Troubleshooting steps when oil pressure does not regulate correctly in automatic mode.

VSOP Drive Daily Shutdown and Autostart

Addresses the issue of the VSOP drive shutting down and autostarting daily.

Reverse Oil Pump Motor Rotation

Steps to correct reverse rotation of the oil pump motor.

Drive Replacement Instructions

Most Frequently Asked Questions

Motor Rotation vs. Input Wiring

Explains why motor rotation doesn't change with input wiring modifications on the VSOP drive.

Oil Pressure Regulation Process

Details the process of oil pressure regulation using the programmed setpoint and VSOP drive speed.

50 Hz Installation - 60 Hz Operation

Explains how the VSOP drive can operate at 60 Hz on a 50 Hz installation.

SSS vs. VSOP Drive Differences

Differentiates between Solid State Starters (SSS) and VSOP drives in motor control.

Remote Keypad Unit

Operating Instructions

Provides instructions for using the Remote Keypad Unit with the VSOP drive.

Service Parts List

YK Mod E Chillers Only

VSD Oil Pump General Information

Covers changes for the Mod. "E" chiller regarding the VSD oil pump drive.

VSD Oil Pump Drive Overview

States that the VSOP drive in Mod. "E" YK chillers is the same as in Mod. "D".

Safety Shutdowns - Mod E Chillers

Pressure Setpoint Not Achieved

Details safety shutdown when the pressure setpoint is not met, replacing the "HIGH OIL FLOW" message.

VSOP Drive Okay Relay

Explains the function of the VSOP drive okay relay and its role in cycling shutdown detection.

Auto Re-settable Shutdowns

Refers to troubleshooting guide for auto-resettable shutdowns on Mod. "D" chillers.

Non Auto Resettable Shutdowns

Refers to troubleshooting guide for non-auto-resettable shutdowns on Mod. "D" chillers.

Diagnostic Software

Notes that diagnostic software no longer supports the VSOP drive directly.

Troubleshooting Guide (Mod E Chillers)

Blown Input Fuses or Status LED Not Lit

Troubleshooting steps for blown fuses or an unlit status LED on the VSOP drive for Mod E.

Control Center AUTOSTART, VSOP LED Flashing RED (Mod E)

Addresses AUTOSTART display and flashing red LED on VSOP drive for Mod E.

Control Center AUTOSTART, VSOP LED Constant RED (Mod E)

Troubleshoots AUTOSTART display and constant red LED on VSOP drive for Mod E.

VSOP Drive Won't Start, Status LED Constant RED (Mod E)

Diagnoses VSOP drive startup failure with a constant red LED for Mod E.

Oil Pressure and LED Status Issues (Mod E)

Oil Pressure Not Regulating to Setpoint (Mod E)

Troubleshooting steps for oil pressure regulation failure in automatic mode for Mod E.

Shutdown on Low Differential Pressure with Green LED (Mod E)

Addresses shutdown due to low differential oil pressure with a green VSOP drive LED.

VSOP Drive Daily Shutdown and Autostart (Mod E)

Troubleshoots daily shutdown and autostart of the VSOP drive.

Reverse Oil Pump Motor Rotation (Mod E)

Steps to correct reverse rotation of the oil pump motor.