Table 20: Compressor Motor Protection - York Sun Premier GZA1M Series Start-Up & Operation

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Table 20: Compressor Motor Protection

Compressor

Comp 1A HP

Protection

25T SE

Internal O/L

30T SE

Internal O/L

40T SE

11.5

Internal O/L

50T SE

7.5

Internal O/L

25T HE

Internal O/L

30T HE

18.5

Internal O/L

40T HE

Internal O/L

50T HE

17.5

Internal O/L

25T HC

Internal O/L

30T HC

8.5

Internal O/L

40T HC

Internal O/L

50T HC

8.5

Internal O/L

NOTES:

SE = Standard Efficiency HE = High Efficiency HC = High Capacity NA = Not Available O/L = Overload

Liquid Line High Pressure Unloading

This sequence helps to prevent nuisance safety

chain trips and safety chain lockouts in the event

of dirty condenser coils or extreme outdoor ambi-

ent temperatures. The operation is only available on

units equipped with the liquid line transducer option.

When any compressor system is in operation, the

unit controller monitors the liquid line pressure.

When the liquid line pressure exceeds the liquid

line high pressure limit (600 psig) for 10 seconds,

the unit controller:

• Logs a high liquid line pressure alarm and

disables the smallest HP compressor of that

circuit

• Logs the current OAT at the time of the liquid

line pressure alarm

• Recalculates the compressor staging and at-

tempts to continue supply DAT at the active

DAT cooling setpoint

When the liquid line pressure is greater than the

liquid line high pressure limit after 60 seconds, the

unit controller:

• Disables the smallest HP compressor still in

operation

• Recalculates the compressor staging and at-

tempts to continue supply DAT at the active

DAT cooling setpoint

This process is repeated every 60 seconds until

the liquid line pressure falls below the liquid line

high pressure limit or all compressors in the circuit

have been disabled.

YORK

Compressor

Comp 1B HP

Protection

Internal O/L

5.5

Internal O/L

Module

Internal O/L

5.5

Internal O/L

Module

Start-Up & Operation Guide | 5587001-YSG-A-520

Compressor

Comp 2A HP

Protection

4.5

Internal O/L

5.5

Internal O/L

11.5

Internal O/L

7.5

Internal O/L

7.5

Internal O/L

When the final compressor running is a variable

speed drive compressor and the liquid line pres-

sure is still greater than the liquid line high pres-

sure limit, the variable speed drive compressor

speed reduces to the minimum speed for an ad-

ditional minute.

When the pressure is still greater than the liquid line

high pressure limit after the 60 second time delay,

the variable speed drive compressor is disabled.

To clear the high liquid line pressure alarm:

• The liquid line pressure must be 10 psig less

than the liquid line high pressure limit for 10

minutes

• The current OAT must be 5.0°F less than the

OAT logged at the time of the initial high liq-

uid line pressure alarm

When any compressor is disabled 3 times within

a 120 minute window, that compressor enters a

safety lockout and a manual rest is required.

When a liquid line pressure transducer becomes

unreliable, high pressure discharge unloading is

disabled.

Suction Line Low Pressure Unloading

This sequence helps prevent nuisance safety

chain trips and safety chain lockouts in the event

of dirty air filters/evaporator coils, low airflow con-

ditions, or low ambient temperatures. The opera-

tion is only available on units equipped with the

suction line transducer option.

Compressor

Comp 2B HP

Protection

Internal O/L

7.5

Internal O/L

8.5

Internal O/L

7.5

Internal O/L

7.5

Internal O/L

7.5

Internal O/L

8.5

Module

Internal O/L

Table of Contents

Table 20: Compressor Motor Protection - York Sun Premier GZA1M Series Start-Up & Operation

Table 20: Compressor Motor Protection

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