Cornelius SERIES 1100 (R22) Manual download pdf (Page 10)

ZB Series

Application Guide

Models ZB95KQ/E and ZB114KQ/E with motor protection code “W” use

a combination of sensors and an electronic module (INT69SU) for motor

protection. For the INT69SU, there are four PTC (positive temperature

coefficient) internal thermisters connected in series that react with

avalanche resistance in the event of high temperatures. All four are used

to sense motor temperature. The thermister circuit is connected to the

protector module terminals S1 and S2. When any thermister reaches a

limiting value, the module interrupts the control circuit and shuts off the

compressor. After the thermister has cooled sufficiently, the resistance

will decrease, thus allowing the module to reset. However, the module

has a 30-minute time delay before reset after a thermister trip. If the

INT69SU module is applied in conjunction with a Programmable Logic

Controller, it is important that a minimum load is carried through the

M1-M2 control circuit contacts. The minimum required current through

the module relay contacts needs to be greater than 100 milliamps but

not to exceed 5 amps. If this minimum current is not maintained, this has

a detrimental effect upon the long-term contact resistance of the relay

and may result in false compressor trips. PLC operated control circuits may

not always provide this minimum current. In these cases modifications to

the PLC control circuit are required. Consult your application engineering

department for details.

3. Compressor Information

3.1 Fusite (Terminal)

Fusite (Terminal) pin orientation for single-phase and three phase

refrigeration scroll compressors are shown in Figure 1 and inside the

terminal box.

3.2 Rotation Direction of Three Phase Scroll Compressors

Scroll compressors will only compress in one rotational direction.

Direction of rotation is not an issue with single phase compressors since

they will always start and run in the proper direction. Three phase

compressors will rotate in either direction depending upon phasing of

the power. Since there is a 50-50 chance of connecting power in such a

way as to cause rotation in the reverse direction, it is important to include

notices and instructions in appropriate locations on the equipment to

ensure proper rotation direction when the system is installed and

operated. Verification of proper rotation direction is made by observing

that suction pressure drops and discharge pressure rises when the

compressor is energized. Reverse rotation of a scroll compressor also

results in substantially reduced current draw compared to specification

sheet values. Suction temperature will be high, discharge temperature

will be low and the compressor may be abnormally noisy There is no

negative impact on durability caused by operating three phase Copeland

Scroll compressors in the reversed direction for a short period of time

(under one hour), In models ZB58 - ZB114 oil may be lost. This oil loss

can be prevented during reverse rotation if the suction tubing is routed

at least six inches (15 cm) above the compressor. After several minutes of

operation in reverse, the compressor's motor protection system will trip the

compressor off. If allowed to repeatedly restart and run in reverse without

correcting the situation, the compressor will be permanently damaged.

All three phase scroll compressors are identically wired internally. As a

result, once the correct phasing is determined for a specific system or

installation, connecting properly phased power leads to the same

terminals will maintain proper rotation direction.

Motor Terminal (Fusite) Connections for

Single Phase and Three Phase Scrolls

Figure 1

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 69 70

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Cornelius SERIES 1100 (R22) Manual Page 10

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