eti precision PI-250B Users guide

PORTABLE CURRENT SOURCE FOR

CIRCUIT BREAKER AND MOTOR OVERLOAD TESTING

INSTRUCTION MANUAL

PI-250B

Release 20

November 9, 2019

Electrical Test Instruments, LLC

1301 Avondale Road, Suite J

New Windsor, MD 21776

(410) 857-1880

Fax (410) 857-1387

www.ETIPrecision.com

Electrical Test Instruments PI-250B Table of Contents

TABLE OF CONTENTS

SECTION I: GENERAL INFORMATION and SPECIFICATIONS

WARNING

I-1

About This Manual

I-1

Introduction

I-3

General Description

I-3

Specifications

I-4

SECTION II: DETAILED DESCRIPTION

High Current Test Sets

II-1

PI-250B Unit Circuitry

II-1

Major Parts Identification and Operation

II-2

Front Panel

II-3

SECTION III: OPERATING INSTRUCTIONS

Pre-Test Installation and Setup

IV-1

Basic Guidelines and Suggestions

IV-3

Single Pole Molded Case Breakers

IV-4

Multi-pole Molded Case Breakers

IV-7

Low Voltage Power Breakers

IV-10

Motor Overload Relays

IV-14

Ratioing Current Transformers

IV-16

SECTION IV: SERVICE INFORMATION AND DOCUMENTATION

Basic Maintenance and Calibration

V-1

Parts List

V-1

Warranty

V-3

Overall Schematic

V-4

Electrical Test Instruments PI-250B Table of Contents

SECTION I

GENERAL INFORMATION

Electrical Test Instruments PI-250B Section II – Detailed Description

Page II - 1

WARNING

WARNING - READ THIS ENTIRE MANUAL AND

THOROUGHLY FAMILIARIZE YOURSELF WITH THE UNIT

OPERATION PRIOR TO CONNECTING THE UNIT TO A

SOURCE OF POWER. HIGH CURRENT TEST SETS ARE

NORMALLY POWERED FROM HIGH CAPACITY MAINS,

AND IMPROPER CONNECTION OR OPERATION COULD

CAUSE DAMAGE TO THE TEST SET AND EQUIPMENT

UNDER TEST, AS WELL AS CREATE AN UNSAFE

CONDITION FOR PERSONS OPERATING THE SET.

Electrical Test Instruments PI-250B Section II – Detailed Description

Page II - 2

ABOUT THIS MANUAL This manual consists of completely new descriptive, operational, and technical

information, based on many years of experience in the design, manufacturing, and operation of electrical protective device test equipment. It is intended to provide useful, up-to-date and complete information for safe and efficient operation of the test set.

INTRODUCTION A high current test set is designed with high current, low voltage outputs used

for many purposes, including primary injection testing of direct acting low voltage circuit breakers, motor overload relays, current transformers. It also can be used as a general purpose adjustable voltage or current source. The front panel displays provide simple indication of output current, time, and system status. The keyboard provides easy control of output.

GENERAL DESCRIPTION The PI-250B features digital readout of current and time enhanced by digital

signal processing. Automatic pulse (memory) mode provides fast and accurate evaluation of output current pulses as short as one half cycle.

The PI-250B incorporates a PIC microcontroller with a precision A/D converter and special firmware for true-RMS continuous and pulse current reading with high accuracy. It also utilizes a sophisticated current sensing system for more reliable current latch mode operation and better timing accuracy. An LED 4 digit readout for current in eight ranges from 5.000 A to 1000 A full scale with automatic overrange detection reduces the chance of operator error. An integral auto ranging timer with LED readout provides four digits in seconds or cycles mode, with a resolution of 0.001 second or 0.1 cycle. The entire metering and control package is combined on a single PCB which can be removed and replaced very easily, for efficient maintenance and repair.

The PI-250B provides four output taps which range from 0-3 volts at 250 amps to 0-120 volts at 5 amps, continuous, and pulse output up to 5x. The high current outputs use bus bar and convenient thumb screws for connection of heavy cables, and the lower current outputs use heavy duty binding posts which accommodate banana plugs and smaller wires.

The unit is housed in a rugged, lightweight aluminum case with a waterresistant seal, and a removable lid which has room for storage of power cord and output leads. The front panel is a durable plastic overlay which can be wiped clean easily and safely, and the tactile keypad provides long-lasting and reliable operation with positive operator feedback.

Electrical Test Instruments PI-250B Section II – Detailed Description

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SPECIFICATIONS for PI-250B

Input: 120 VAC +/- 10%, 50/60 Hz

600 VA Continuous, 3 kVA Peak

Output: 0-3 VAC 250 A 30 min on 30 min off

500 A 3 min on 8 min off 750 A 30 sec on 4 min off 1000 A 1 sec on 1 min off

0-6 VAC 125 A 30 min on 30 min off 250 A 3 min on 8 min off 375 A 30 sec on 4 min off 500 A 1 sec on 1 min off

0-24 VAC 25 A 30 min on 30 min off 50 A 3 min on 8 min off 75 A 30 sec on 4 min off 125 A 1 sec on 1 min off

0-120 VAC 5 A 30 min on 30 min off 10 A 3 min on 8 min off 15 A 30 sec on 4 min off 25 A 1 sec on 1 min off

CURRENT RANGES:

10.00 / 25.00 / 50.00 / 100.0 / 250.0 / 500.0 / 1000 Amperes

CURRENT ACCURACY:

+/- 0.5% Reading + 0.5% Range + 1 Digit (Continuous) +/- 1.0% Reading + 1.0% Range + 1 Digit (Pulse > 0.01 sec)

TIMER RANGES:

0-9.999 / 99.99 / 999.9 / 9999 Seconds 0-999.9 / 9999 Cycles

TIMER ACCURACY:

+/- 0.005 sec +/- 0.005% of reading +/- 1 count

DIMENSIONS AND NET WEIGHT

Height: 12.0 in. (178 mm) Width: 13.0 in. (483 mm) Depth: 9.0 in. (152 mm) Weight: 35 lb. (4.55 kg)

STANDARD ACCESSORIES

Cable Lug Adapter 2 pcs Contact Leads 1 pair High current leads 1 pair

Electrical Test Instruments PI-250B Section II – Detailed Description

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SECTION II

DETAILED DESCRIPTION

Electrical Test Instruments PI-250B Section II – Detailed Description

Page II - 5

SECTION II

DETAILED DESCRIPTION

High Current Test Sets High current test sets generally consist of the following:

1) A continuous (Vernier) or step-adjustable AC voltage.

2) An output transformer with one or more isolated low voltage, high current

secondaries.

3) Power control circuitry consisting of switches, relays, SCRs, protective

devices, etc.

4) Current measurement circuitry consisting of sensors, current meter, and

timer.

In general, a primary voltage is selected by means of a combination of coarse tap and Vernier adjustment. This voltage is applied to the output transformer and stepped down to provide the desired current into the load impedance.

Since the load is usually inductive, the output initiation should correspond to a phase delay of up to 90 degrees (voltage peak). This tends to minimize the DC offset which results when an inductive load is energized at or near the voltage zero-crossing.

Many modern test sets use solid-state SCR controllers, with electronic circuitry to provide precise phase control of initial firing angle.

PI-250B Circuitry The PI-250B uses a 120 VAC supply for main power, using a standard IEC input

connector and a rocker switch. A 12 VDC switching supply provides control voltage for the instrumentation, which also has a 5 VDC supply for logic circuitry, and +/- 12 VDC for analog circuitry.

There is a solid-state SCR controller which provides power to the variable autotransformer, which is may be set to 0-100%. This variable output voltage is connected to the primary of the output transformer through a circuit breaker. The four output taps are provided for connection to the device under test.

The common lead of the output transformer is wired through a PCB mounted current transformer. The PC board provides signal conditioning and measurement by means of a microcontroller (PIC), which has a 10 bit A/D converter. The firmware responds to operator keypad input to perform control and measurement functions. An RS-232 connection is used to provide current

Electrical Test Instruments PI-250B Section II – Detailed Description

Page II - 6

and time measurements on two 4-digit seven segment LED displays. There is also a continuity sensor which can monitor contact state or be used as a remote initiate.

Major Parts Identification and Operation

Power Inlet: This is a standard IEC power inlet jack which accepts removable line cords. A right-angle cord is provided which routes the input power cord toward the rear of the unit.

On/Off Switch: This rocker switch controls the input power to the PI-250B. Vernier: This is a variable autotransformer which can be adjusted from 0 to

100% of line voltage, corresponding to a range of output current. Circuit Breaker: This 10-amp circuit breaker protects the output of the Vernier.

It will pop out under an extended or extreme overload, and must be pushed to reset (after a short period of time).

Current Display: This 4 digit 7 segment red LED display shows the current being produced from the output terminals of the test set. It can be selected in 8 ranges to read full scale currents from 5.000 amps full scale to 1000 amps full scale, and can give readings up to 50% higher before indicating an overrange condition.

Time Display: This 4 digit 7 segment red LED display shows the time that output current has been flowing. It is auto ranging from 0.001 to 9999 seconds, or 000.1 to 9999 cycles.

Output Terminal Board: This is where the output current from the test set may be connected to cables and the device under test. The 3V 250A and 6V 100A connections, and the associated common terminal, are bus bars with ¼”-20 thumb screws for convenient connection to heavy cables. The 24V 25A and 120V 5A connections, and their common terminal, are heavy duty binding posts for banana jacks or smaller wires.

Power ON Indicator: This green LED indicates that power is turned on and the control circuitry is operating properly.

Output ON Indicator: This yellow LED indicates that power is being supplied to the output terminals.

Continuity Indicator: This green LED indicates that continuity is present at the contacts jacks.

Contacts Jacks: These banana jacks provide a small AC signal which determines if there is continuity. They may be used to monitor auxiliary contacts on a protective device, or as a remote initiate in Current Latch mode.

Initiate Key: This button initiates the output of the test set. It will also reset the current and time displays.

Electrical Test Instruments PI-250B Section II – Detailed Description

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Stop Key: This button turns off the output of the test set. It may also be held for two seconds to reset the displays.

MOM Key: This button puts the controls in momentary mode, where output will stay on only while the initiate key (or remote switch) is held.

MAINT Key: This button activates the maintained, or latch function, where the output will remain on until the Stop key is pressed. MAINT function is disabled for remote initiate.

SEC Key: This button selects time reading in seconds. CYC Key: This button selects time reading in cycles, based on 60 Hz line

frequency. RANGE Key: This button shows the current display range, which may be 5.000

to 1000 amps full scale. Holding this button for more than one second will cycle the ranges through all eight selections.

MODE Key: This button shows the operational mode of the test set. Default is C.L., or current latch, which performs timing while current is present and shuts off the test when current stops. If this key is held more than one second, the display will cycle through N.O. and N.C. modes, for Normally Open and Normally Closed contacts. The contacts must be in their normal state to initiate output, and current must be detected to latch on in MAINT mode. Output is turned off when contacts change state.

eti precision PI-250B Users guide

Specifications and Main Features

Frequently Asked Questions

User Manual