Carrier 19XL specifications Starting Equipment, Unit-Mounted Solid-State Starter Optional

STARTING EQUIPMENT

The 19XL requires a motor starter to operate the centrif- ugal hermetic compressor motor, the oil pump, and various auxiliary equipment. The starter serves as the main ®eld wiring interface for the contractor.

Three types of starters are available from Carrier Cor- poration: solid-state, wye-delta, and across-the-line starters. See Carrier Speci®cation Z-375 for speci®c starter require- ments. All starters must meet these speci®cations in order to properly start and satisfy mechanical safety requirements. Starters may be supplied as separate, free-standing units, or may be mounted directly on the chiller (unit mounted) for low-voltage units only.

Inside the starter are 3 separate circuit breakers. Circuit breaker CB1 is the compressor motor circuit breaker. The disconnect switch on the starter front cover is connected to this breaker. Circuit breaker CB1 supplies power to the com- pressor motor.

The main circuit breaker (CB1) on the front of the starter disconnects the main motor current only. Power is still energized for the other circuits. Two more circuit break- ers inside the starter must be turned off to disconnect power to the oil pump, PIC controls, and oil heater.

Circuit breaker CB2 supplies power to the control center, oil heater, and portions of the starter controls. Circuit breaker CB3 supplies power to oil pump. Both of these circuit break- ers are wired in parallel with CB1 so that power is supplied to them if the CB1 disconnect is open.

All starters are shipped with a Carrier control module called the Starter Management Module (SMM). This module controls and monitors all aspects of the starter. See the Con- trols section on page 11 for additional SMM information. All starter replacement parts are supplied by the starter manufacturer.

Unit-Mounted Solid-State Starter (Optional)

ÐThe 19XL may be equipped with a solid-state, reduced- voltage starter (Fig. 5 and 6). This starter provides on-off control of the compressor motor as its primary function. Using this type of starter reduces the peak starting torque, reduces the motor inrush current, and decreases mechanical shock. This is summed up by the phrase ``soft starting.''

Two varieties of solid-state starters are available as a 19XL option (factory supplied and installed). When a unit-mounted, optional, solid-state starter is purchased with the 19XL, a Benshaw, Inc. solid-state starter will be shipped with the unit. See Fig. 5. The solid-state starter's manufacturer name will be located inside the starter access door. See Fig. 6.

These starters operate by reducing the starting voltage. The starting torque of a motor at full voltage is typically 125% to 175% of the running torque. When the voltage and the current are reduced at start-up, the starting torque is reduced as well. The object is to reduce the starting voltage to just the voltage necessary to develop the torque required to get the motor moving. The voltage and current are then ramped up in a desired period of time. The voltage is reduced through the use of silicon controlled recti®ers (SCR). Once full volt- age is reached, a bypass contactor is energized to bypass the SCRs.

When voltage is supplied to the solid-state circuitry, the heat sinks within the starter are at line voltage. Do not touch the heat sinks while voltage is present or serious injury will result.

LEGEND

1Ð Field Wiring Terminal Strips (TB2 and TB3)

2Ð Circuit Breaker 1, 2, 3, 4

3Ð Overload Unit

4Ð Solid-State Controller

5Ð Silicon Controlled Recti®er (SCR) LED (One of 6)

6Ð Starter Fault and Run LEDs

7Ð Voltmeter (Optional)

8Ð Ammeter (Optional)

9Ð SCR (One of 6)

10Ð Voltage LED

11Ð Starter Management Module (SMM)

12Ð Pilot Relays (PR1 to PR5)

13Ð Starter Access Door

Fig. 5 Ð Benshaw, Inc. Solid-State Starter,

Internal View

Fig. 6 Ð Typical Starter External View

(Solid-State Starter Shown)

There are a number of LEDs (light-emitting diodes) that are useful in troubleshooting and starter check-out on Benshaw, Inc. solid-state starters. These are used to indicate:

·voltage to the SCRs

·SCR control voltage

·power indication

·proper phasing for rotation

·start circuit energized

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