Standard Components of Trane Starters. Trane Drives, CVHG, Starters, CVHF, Electrical Components, CVHE, CDHG, CDHF

CTV-PRB004.book Page 10 Sunday, December 18, 2011 6:39 PM

Chiller Selection and Electrical Specification

Standard Components of Trane Starters

• A 4 kVA control-power transformer (CPT) supports all of the chiller auxiliary power needs—

3 kVA control-power transformer supplied with AFDs.

• Primary and secondary current transformers (CTs) support the overload and momentary power loss protection functions of the unit controller.This allows amps per phase and percent amps to be displayed at the unit controller.

• Potential transformers (PTs) support motor protection functions such as under/overvoltage within the unit controller. This allows voltage per phase, kilowatts, and power factor to be displayed at the unit controller.

• Grounding provisions are standard.

• A terminal block for line power connection is standard. Load-side lugs are standard for remote starters.The lug sizes and configuration are shown on the submittal drawing.TheTrane

® AFD has a circuit breaker as standard. Medium-voltage starters have provisions for a bolted connection.

Chiller Selection Report

The following terms are found on a typical TOPSS product report. Review the example selection output report shown in Figure 4, p. 12 .

Electrical information

Usually the primary RLA (incoming line), compressor motor RLA, and kW of the chiller are used as nameplate values. In this section, we will review the typical electrical data presented on the selection report.

A. Motor size (kW).

The motor size is listed on the program report based on its output kW.The

output kW is the motor’s full, rated power capacity.There is an amperage draw associated with the motor size called full-load amps (FLA). FLA is the amperage the motor would draw if it were loaded to its full rated capacity, i.e. the motor size. The FLA is not available from the chiller selection program, but it can be obtained from motor data sheets upon request.

B. Primary power (kW).

The primary power is the power the chiller uses at its design cooling capacity. The primary power will always be less than or equal to the motor size.

C. Motor locked-rotor amps (LRA).

There is a specific locked-rotor amperage value associated with each specific motor. This is the current draw that would occur if the rotor shaft were instantaneously held stationary within a running motor. LRA is typically six to eight times the motor full-load amps (FLA). LRA is also used commonly in discussing different starter types and the inrush amperages associated with the motor start. For example, a wye-delta starter will typically draw approximately 33 percent of the motor LRA to start. A solid-state starter will draw approximately 45 percent of the motor LRA to start.

D. Primary rated-load amps (RLA [incoming line]).

The RLA is also commonly referred to as the selection RLA or unit RLA.This is the amperage that is drawn on the line side when the chiller is at full cooling capacity. Nameplate RLA (usually the same as primary RLA [incoming line]) is the key number used to size the starter, disconnects, and circuit breaker. Primary RLA (incoming line) is also the value used to determine the minimum circuit ampacity (MCA) for sizing conductors.

Primary RLA (incoming line) is always less than or equal to the motor full-load amps (FLA).

E. Compressor motor RLA.

This is the amperage between the motor and starter or AFD. If the unit is a starter, the compressor motor RLA will be almost identical to the primary RLA (incoming line). If the unit is an AFD, typically, the compressor motor RLA will be larger. This value is used to size the AFD.The primary RLA (incoming line) is lower due to the improved power factor of the

AFD.

10 CTV-PRB004-EN



F. Minimum circuit ampacity (MCA).

This term appears on the chiller nameplate and is used by the electrical engineer to determine the size and number of conductors needed to bring power to the starter.

MCA = 1.25 x (Primary RLA [incoming line])+

( 4000 volts motor

)

… with this number rounded up to the next whole number. Said another way, the MCA is

125 percent of the motor design primary RLA (incoming line) plus 100 percent of the amperage of other loads (sump heater, oil pump, purge, etc.).The MCA is listed on the chiller selection report.

Power cable sizes and conduits are discussed in “Electrical System–PowerWire Sizing,” p. 56 . If the

AFD is a remote, free-standing AFD, the MCA will be based on the compressor motor RLA.

G. Maximum overcurrent protection (MOP or MOCP).

The MOP appears on the chiller nameplate. The electrical engineer often wants to know the MOP when the chiller is selected for sizing fuses and upstream circuit breakers. Understand that the MOP is a maximum, NOT a recommended fuse size. Improperly sized circuit breakers or fuses can result in nuisance trips during the starting of the chiller or insufficient electrical protection. MOP is also NOT used to size incoming power wiring—the MCA is used for this purpose.

CTV-PRB004-EN 11



Figure 4.

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Motor Protection

Historically, motor protection was provided in the starter by some type of monitoring system.

Starter manufacturers usually provide a full range of optional equipment mounted on the starter.

Eaton Cutler-Hammer ® offers IQ metering and motor protection products for their starters.

Today,Trane provides most of the key motor protection and metering functions (see Table 2 , first column) within the chiller microprocessor control panel as standard. Having the motor control and chiller control in one panel provides better integration and optimization of the two control systems.

For example, the chiller controller can unload the chiller when approaching an overload “trip” point, so that the chiller stays online.

Table 2 and Table 3, p. 14 can be used to compare the standard electrical features of the chiller controller with those of other common Eaton Cutler-Hammer ® starter-only-mounted devices.

Additional starter-mounted metering and motor protection may not be required and could be considered redundant. These devices are not available for AFDs.

Table 2.

Protection and functions by motor packages

Protection Functions

Communications

Ground fault

Long acceleration

Maximum number of starts

Momentary power loss (distribution fault)

Motor overload

Motor winding temperature

Over temperature

Overvoltage

Phase imbalance

Phase loss

Phase reversal

Run timer

Separate alarm levels (f)

Surge capacitor/lightning arrestor

Undervoltage

Tracer

AdaptiView

Optional

Optional (b)

Standard

Standard

Standard

Standard

Standard (c)

Standard

Standard (e)

Standard

Standard

Standard

Standard

Standard

Optional

Standard (e)

MP 3000

Optional

Standard

Standard

Standard

N/A

Standard

Optional (d)

N/A

N/A

Standard

Standard

N/A

Standard

Standard

N/A

N/A

(a) IQ 150

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

Optional

N/A

N/A

N/A

IQ DP 4130

N/A

N/A

N/A

N/A

Optional

N/A

N/A

N/A

Standard

Standard

Standard

Standard

N/A

N/A

N/A

Standard

(a) The MP 3000 features Intel-I-Trip overload protection, enhanced custom trip curve development, UL 1053 ground fault, and advanced data logging and diagnostics.

(b) For low voltage, a Trane-supplied circuit breaker or non-fused disconnect is also required when ground fault is specified.

(c) The chiller controller monitors the motor temperatures of all three phases with one resistance temperature detector (RTD) per phase

(d) For this option, add one or two sets (three RTDs per set) of 100-ohm platinum RTDs to the motor. Contact La Crosse Field Sales Support.

(e) Under/over phase-voltage sensors include volts per phase, kW, power factor, kWh, and under/overvoltage. A required pick on medium-voltage starters.

(f) Three alarm levels are used: warning only, nonlatching (auto-reset), and latching (manual reset required).

CTV-PRB004-EN 13



Table 3.

Starter ONLY: metering functions and accuracies

Metering Functions

Ampere demand

Tracer AdaptiView

N/A

MP 3000 (a)

N/A

IQ 150

Standard (±0.25%)

IQ DP 4130

Standard (±0.3%)

Current (%RLA)

Current (3-phase)

Voltage (3-phase)

Frequency

Standard (±3% to ±7%) Standard

Standard (±3%) Standard

Standard (b) (±2%)

N/A

N/A

N/A

N/A

N/A

Standard (b) (±5%)

Standard (b) (±5%)

N/A

N/A

N/A

N/A

N/A

Standard (±0.25%)

Standard (±0.25%)

Standard

N/A

Standard (±0.3%)

Standard (±0.3%)

Standard

Standard (31 st )

Standard (31 st )

Harmonic distortion current

Harmonic distortion voltage

Kilowatt

Power factor

VA (volt-amperes)

VA demand

VA hours

VARs (volt-amperes reactive)

VAR demand

VAR-hours

Watt, see Kilowatt

Watt demand

N/A

N/A

N/A

N/A

N/A

N/A

Standard (b)

Standard

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

N/A

Standard

Standard (±0.5%)

Standard (±0.5%)

Standard (±0.5%)

Standard (±0.5%)

Standard (±0.5%)

Standard (±0.5%)

Standard (±0.5%)

Standard (±0.5%)

N/A

Standard

Standard (±0.6%)

Standard (±0.6%)

Standard

Standard (±0.6%)

Standard (±0.6%)

Standard

Standard (±0.6%)

Standard (±0.6%)

Watt-hours Standard N/A Standard (±0.5%) Standard

(a) The MP 3000 features Intel-I-Trip overload protection, enhanced custom trip curve development, UL 1053 ground fault, and advanced data logging and diagnostics.

(b) Under/over phase-voltage sensors include volts per phase, kW, power factor, kWh, and under/overvoltage. A required pick on medium-voltage starters.

Overload protection

Overload or overcurrent protection shields the motor from small levels of overcurrent ranging from

107 to 140 percent of the primary RLA of the chiller. In contrast, fuses and circuit breakers are used to protect against short-circuit currents which may range to well over 100,000 amps.

Inductive loads, such as a chiller motor, behave differently than resistive loads such as electric heaters. Their current draw is greatest at startup and corresponds to the existing load when running. In other words, a motor operating normally draws rated amps (RLA) at rated load, fewer amps at less-than-rated load and more amps at greater-than-rated load. It is the latter condition that requires overload protection.

Adding an overload protection device prevents the motor from drawing more than its rated amperage for an extended period. Basic overload devices simply open the circuit when current draw reaches the “trip” point. More sophisticated devices attempt to restore normal motor operating conditions by reducing the load, but will disconnect the motor if overloading persists.

As with most overload devices, the chiller controller determines the “trip time” by measuring the magnitude of the overload. It then compares the overload to the programmed RLA “time-to-trip” curve. At startup, the standard overload protection is bypassed for the starter’s acceleration time, or until the motor is up to speed. Refer to Figure 5, p. 15 for the chiller controller’s overload timeto-trip curve.

14 CTV-PRB004-EN


CTV-PRB004-EN


Figure 5.

Tracer AdaptiView chiller controller overload time-to-trip curves

25

20

Overload Trip

Time (sec)

15

10

5

0

Nominal

Minimum

Maximum

102 108 114 120 126 132 138 144 150

% Run-Load Amps

Overload situations, left unchecked by protection, can cause excessive motor heat, that can permanently damage the windings and lead to motor failure. The time until motor damage depends mainly on the magnitude of the overcurrent and has an inverse time versus current relationship. The greater the overcurrent, the less time it takes to cause motor damage.

Overcurrent can be the result of motor overload, low line voltage, unbalanced line voltage, blocked load (rotor cannot freely rotate), single phasing, bad connections, broken leads, or other causes.

It can occur in any one winding, a set of windings, or in all the motor windings.

The threshold of overcurrent is generally the primary RLA, which may be raised for service factor or lowered due to any derating factor, such as ambient temperature or line-voltage imbalance.

Overload protection is bypassed during a start due to the high currents associated with locked rotor and motor acceleration. Maximum allowed acceleration times per the AdaptiView unit controller are listed in Table 4 .

Table 4.

Long acceleration protection

Starting Method

(starter type)

Wye-Delta

Solid-State

Variable-Frequency Drive

Across-the-Line

Primary Reactor

Autotransformer

27

12

6

16

16

Maximum Setting for the

Acceleration Timer (sec)

27

Motor overheat protection

The unit controller monitors the motor winding temperatures in each phase and terminates chiller operation when the temperature is excessive. This feature also prevents the chiller from starting if the motor temperature is too high.

Momentary power loss protection (distribution fault)

Momentary power losses longer than two or three line cycles will be detected and cause the chiller to shut down, typically within six cycles.The chiller can also shut down due to excessive or rapid voltage sags. Shutting down the chiller prevents power from being reapplied with different motor phasing.

15



Phase failure/loss protection

The chiller will shut down if any of the three-phases of current feeding the motor drop below

10 percent RLA for 2.5 seconds.

Phase imbalance protection

Based on an average of the three phases of current, the ultimate phase-imbalance trip point is

30 percent.The RLA of the motor can be derated depending on the percent of this imbalance.The

phase-imbalance trip point varies based on the motor load.

Phase reversal protection

Detects reverse-phase rotation and shuts the chiller down (backwards rotation).

Under/overvoltage protection

The chiller is shut down with an automatic reset due to excessive line voltage ±10 percent of the design voltage.

Short cycling protection

Prevents excessive wear on the motor and starter due to heating from successive starts.The unit controller uses an algorithm based on a motor heating constant and a background timer

(measuring the running time since the last start).

Supplemental motor protection

This is a set of optional motor protection features, offered as a option in addition to the Enhanced

Electrical Protection Package (see “SMP, Supplemental Motor Protection—Medium voltage only

(Enhanced Electrical Protection Package option),” p. 66 ).

16 CTV-PRB004-EN


Low-Voltage Starter Types

Table 5 shows the most common low-voltage starter types available and lists their advantages and disadvantages.Typical inrush acceleration profiles for these starters are shown in Figure 6, p. 18 .

It is very uncommon to see a full-voltage starter in a low-voltage application due to the high inrush current; however, it is represented on the chart to provide a frame of reference.

Which starter type is best?

The wye-delta starter has been around a long time and, except for an AFD, it draws the lowest inrush current.Wye-delta starters are electromechanical and service technicians are typically more comfortable with them. The solid-state starter is a relatively newer design compared to the wyedelta, and has a slightly higher inrush current in chiller applications.The solid-state starter inrush can be set lower (the starter takes longer to get the motor up to speed), but it must be above the minimum inrush required to develop the proper starting torque. The solid-state starter is comparable in price to the wye-delta starter and has a smoother inrush curve without any current spikes.The wye-delta’s transition spike is not long enough to set utility demand ratchets or reduce the life of the motor. The starter type chosen ultimately depends on the application.

Table 5.

Comparison of low-voltage starter types

Starter Type

(closed-transition

Inrush

Current

% LRA

Percent

Rated

Torque

How

Often

Used

Wye-Delta

(Star-Delta)

Solid-State

Adaptive Frequency

Drive (AFD)

33

~45

<13

(<RLA)

33

33 varies

60%

15%

25%

Advantages Disadvantages

Typical

Acceleration

Time

(seconds)

• Equal reduction of torque and inrush current

• Low cost

• Can be unit mounted

• Only applicable up to

600 volts

• “Spike” at transition

• Lowest inrush current

• Better chiller efficiency at reduced lift

• Most expensive

• Efficiency loss at full load

• Harmonics may be an issue

5–12

• Gradual inrush/ramp up

• No “spike” at transition

• Price comparable to the wyedelta

• Higher level of service expertise than wye-delta

• Higher inrush current than wye-delta

• Starting harmonics may be an issue

5–12

8–30

Trane Adaptive Frequency Drives provide motor control, but they are much more than just starters.

They also control the operating speed of the compressor-motor by regulating output voltage in proportion to output frequency. Varying the speed of the compressor-motor can translate into significant energy savings.

Applications that favor the use of an AFD exhibit increased operating hours at reduced condenser water temperatures and high energy costs. However, it is important to recognize that all variablespeed drives, including theTrane AFD, require more energy near full-load design conditions, often coinciding with the peak electrical demand of the building. This may result in higher demand charges and diminish the overall energy savings. An analysis of the full-year operation of the chiller plant using an hour-by-hour simulation program that does not use blended kW and kWh energy rates will help determine whether an AFD is appropriate for a specific application and location.

Unit or remote mounted?

Unit-mounted starters can save on installed cost and space, and they can be tested in the factory and shipped on the chiller in a NEMA 1 enclosure. Remote-mounted starters provide more options for multiple starter lineups, and may be chosen in order to implement some of the industrial starter options such as high-fault and NEMA 12/3R.

CTV-PRB004-EN 17

Standard Components of Trane Starters. Trane Drives, CVHG, Starters, CVHF, Electrical Components, CVHE, CDHG, CDHF 82 Pages

Standard Components of Trane Starters. Trane Drives, CVHG, Starters, CVHF, Electrical Components, CVHE, CDHG, CDHF

Chiller Selection and Electrical Specification