Load Tap Changer Analyzer LTCA-40

Fast and Accurate Measurements

The LTCA-40 is Amperis winding resistance meter and load tap changer contact analyzer. The LTCA-40 is designed to accurately measure the winding resistance of highly inductive power transformers. The unit’s triple resistance-reading input channels can measure three winding resistances simultaneously, and four-wire (Kelvin) connections provide high accuracy and require no lead compensation. A special feature of this device is its ability to measure and graph the resistance trace of a transformer LTC or voltage regulator contact during operation. One resistance input channel is dedicated to this feature. The LTCA-40 provides stable resistance readings of very large transformers by utilizing a 60 Vdc power supply capable of outputting a test current up to 40 Amperes.

Resistance Reading Features

Three resistance-reading channels can measure resistance from 1 micro-ohm to 500 ohms, and the test current is programmable (1A, 5A, 10A, 40A). The LTCA-40 can also be used to measure EHV ci rcuit-breaker contact resistance, motor winding resistance or any low resistance. If the transformer winding temperature is entered, the LTCA-40 can calculate the equivalent resistance value of the winding material (aluminum or copper) at any standard reference temperature. Also, a special test mode can run a test for up to 45 minutes while saving resistance readings at one-minute intervals.

Dynamic Resistance Test Features

One resistance reading channel is dedicated to dynamic resistance testing. This test can monitor the LTC voltage regulator contact resistance during operation. A resistance graph, plotting resistance over time, can be printed on the built-in thermal printer and is very useful for detecting LTC voltage regulator contact problems.

AC Motor Current Monitoring Feature

One AC current monitoring channel is dedicated to monitoring the LTC voltage regulator motor current during operation. The motor current is also printed on the resistance graph and can help detect LTC voltage regulator motor problems. An AC clamp-on current sensor is provided with the LTCA-40.

Built-in Safety Features

At the end of each test, the LTCA-40 automatically dissipates the stored energy in the transformer. This discharge circuit will continue to work even if the supply voltage is lost.

User Interface

The LTCA-40 features a back-lit LCD screen (64 x 128 dot graphic) that is viewable in both bright sunlight and low-light levels. A rugged, alpha-numeric, membrane keypad is used to control the unit.

Built-in Thermal Printer

The built-in 4.5-inch wide thermal printer can print the breaker contact analysis results in both tabular and graphic formats.

Internal Test Record Storage

The LTCA-40 can store 128 static test records (48 tests per record) and 11 dynamic resistance test records in Flash EEPROM. Test records can be recalled locally or transferred to a PC via the available interfaces (RS-232C port, USB port, USB Flash drive port).

USB Flash Drive Interface and Computer Interface

A built-in USB Flash drive interface provides a convenient method for transferring test records to or from a USB Flash drive. Test records can also be transferred directly to a PC via the RS-232C or USB interface ports. If using a USB Flash drive, test records stored in the LTCA-40’s internal memory can be transferred to the drive, and then the supplied PC software can be used to view the test records stored on the drive. Up to 999 test records can be stored on a USB Flash drive.

Transformer Load Tap Changer Control

Transformer tap positions can be changed remotely using the unit’s built-in transformer load tap changer. This remote-controlled tap changer feature eliminates the need to manually change a transformer’s step-up and step-down taps.

LTCA-40 winding resistance meter details

LTCA-40 winding resistance meter connections

Specifications

Specification	Details
Type	Load tap charger analycer
Physical Specifications	25" Wx8.5"Hx20"D (63.5cmx21.6cmx50cm); Weight: 46lbs (20kg)
Operating voltage	100-240 Vac, 50-60Hz
Resistance reading range	1 uOhms - 500 Ohms
Accuracy	1 - 19.999uOhms: ±0.5% reading, ±1 count
	20 - 999 mOhms: ±1% reading, ±1count
	1 - 500 Ohms: ±1.5% reading, ±1count
Resistance channels	Three static resistance reading channels, One dynamic resistance channel
Test voltage	60 Vdc max
Test currents	1A,5A,10A,40A
Ac Current Input	Clamp-on current sensor, 1-20A
Display	Back-lit LCD Screen (64x128 dot graphic); viewable in bright sunlight and low-light levels
Printer	4.5-Inch wide thermal printer
External data storage	One USB-Flash drive interface port; stores up to 999 test records on a USB Flash drive (not included)
Computer Interfaces	One RS-232C port, One USB port
Internal test record storage	Stores up to 128 static resistance test records (48 test per record) and 11 dynamic resistance test records
Load Tap changer contact	240 Vac, 1A
Safety	Designed to meet UL 61010-a and CAS/CSA C22.2 Nº 1010-1.92 standards
Enviroment	Operating: -10ºC to 50ºC (15ºF to +122ºF); Storage: -30ºC to 70ºC (-22ºF to +158ºF)
Humidity (Max)	90%RH @ 40ºC (104ºF) non-condensing
Altitude (Max)	2000m (6.562 ft) to full safety specifications
Cables	One 50-foot current cable set, Three 50-foot resistance cable sets, One ground cable, One USB cable, One RS-232C cable, One LTC cable, power cord, cable bag
Options	Transportation Case
Warranty	One year on parts and labor