Interview experience
ABB Interview Questions and Answers (2026)
Overview
Section titled “Overview”ABB’s campus process for its power, automation, and robotics engineering roles runs an online test, an optional group discussion, a resume-heavy technical interview, and an HR round that sometimes closes with an unscripted chart-paper case study and a psychometric test.
ABB interview process at a glance
Section titled “ABB interview process at a glance”| Round | Duration | What it tests |
|---|---|---|
| Online Test | ~60 min | Verbal, analytical/logical reasoning, attention to detail, branch-specific technical section |
| Group Discussion (if applicable) | 15-20 min | Communication and structured thinking, added only when applicant volume is high |
| Technical Interview | ~60 min | Resume and projects discussed line by line, plus C++/Java, OOP, DBMS, OS, networking, power-electronics/automation fundamentals |
| HR Interview | 20-30 min | Culture fit; some drives include a chart-paper case-study presentation |
| Psychometric test (select drives) | Varies | Analytical and problem-solving style, ahead of salary discussion |
Online Test
Section titled “Online Test”An elimination round mixing standard aptitude sections (verbal, analytical/logical reasoning, attention to detail) with a technical section that varies by branch - electrical/instrumentation candidates see core-subject questions, CS/IT candidates see programming and CS-fundamentals questions.
Common questions
- Verbal ability and reading comprehension
- Analytical/logical reasoning and attention-to-detail puzzles
- Branch-specific technical MCQs (core electrical/automation for EE, programming fundamentals for CS/IT)
Group Discussion (conditional)
Section titled “Group Discussion (conditional)”Only added when the applicant pool for a drive is large enough to need an extra filter before technical interviews. You get about 5 minutes to prepare before a moderated discussion.
Common questions
- Current-affairs or industry-trend topics (automation, sustainability, electrification)
- Ethics or workplace-culture discussion topics on some campuses
- Structured-thinking prompts scored on articulation and listening, not just talking
Technical Interview
Section titled “Technical Interview”The most distinctive round: a senior ABB engineer works through your resume nearly line by line, questioning design choices and outcomes on every project you list. Some interviewers ask you to name 2-3 domains you’d prefer to go deep on before steering the rest of the conversation there.
Common questions
- Walk through this specific line of your resume - what exactly did you do, and why?
- C++/Java fundamentals, OOP concepts, and basic DBMS/SQL
- Operating systems and computer networking basics
- Core electrical/power-electronics or automation fundamentals (branch-dependent)
- Edge vs. cloud, IoT, or PLC/robotics basics depending on the business unit
Round-by-round breakdowns are on the ABB interview experience page.
HR Interview
Section titled “HR Interview”Evaluates culture fit and communication. Distinctively, some drives close this stage with an unscripted case-study or idea pitch presented to the panel using only chart paper and markers, no slides.
Common questions
- Tell me about yourself and why ABB
- Walk me through a project on your resume - be ready for the interviewer to question almost every line of it
- If asked to pitch an idea to the panel with only a chart paper and markers, how would you structure it?
- ABB is particular about ethics and safety culture - how would you handle a safety-vs-deadline conflict?
Sample answer frameworks for each of these are on the ABB HR interview questions page.
The chart-paper case study and psychometric close
Section titled “The chart-paper case study and psychometric close”On drives that include it, after HR clears you, a final stage layers in a psychometric test (analytical/problem-solving style assessment) ahead of a salary discussion. The chart-paper case study - presenting a business idea or solution on plain paper with markers rather than slides - is a genuine ABB quirk worth practicing for specifically: focus on a clear problem-approach-impact structure rather than visual polish, since you won’t have design tools to lean on.
Common technical interview questions and answers
Section titled “Common technical interview questions and answers”Q: What is the difference between method overloading and method overriding?
Overloading means several methods in the same class share a name but differ in parameter list (type, count, or order); the compiler picks one at compile time, so it is static or compile-time polymorphism. Overriding means a subclass redefines a method it inherited with the same signature; the actual method runs based on the object’s real type at runtime, so it is dynamic or run-time polymorphism, resolved through the virtual table in C++ or dynamic dispatch in Java. Return type alone cannot distinguish overloads. In Java an overriding method cannot reduce visibility and cannot throw broader checked exceptions than the parent.
Q: Why should a base class destructor be declared virtual in C++?
If you delete a derived object through a base class pointer and the base destructor is non-virtual, the behaviour is undefined and in practice only the base destructor runs, so any resources the derived class allocated leak. Declaring the base destructor virtual makes the call go through the vtable, so the derived destructor runs first and then the base destructor runs, which is the correct chain. The cost is one vptr per object and a small indirect call. The rule of thumb is that any class intended to be used polymorphically needs either a public virtual destructor or a protected non-virtual one.
Q: What are the ACID properties, and how would you find the second-highest salary in SQL?
Atomicity means a transaction is all-or-nothing; Consistency means it moves the database from one valid state to another respecting all constraints; Isolation means concurrent transactions do not see each other’s partial work, controlled by isolation levels such as Read Committed or Serializable; Durability means once committed, the change survives a crash, usually guaranteed by a write-ahead log. A portable second-highest-salary query is SELECT MAX(salary) FROM employees WHERE salary NOT IN (SELECT MAX(salary) FROM employees). A cleaner window-function version is SELECT DISTINCT salary FROM (SELECT salary, DENSE_RANK() OVER (ORDER BY salary DESC) AS rnk FROM employees) t WHERE rnk = 2.
Q: What is the difference between a process and a thread?
A process is an independent execution unit with its own virtual address space, file descriptor table, and page tables, while a thread is a unit of scheduling inside a process that shares the code, heap, and open files with its sibling threads but keeps its own stack, registers, and program counter. Because threads share memory, switching between two threads of the same process does not require flushing the TLB or switching page tables, so a thread context switch is significantly cheaper than a process switch. The trade-off is isolation: one thread corrupting shared memory can crash the whole process, whereas a crashing process does not touch its siblings. Shared mutable state also forces you to use mutexes, semaphores, or atomics to avoid race conditions.
Q: What is the difference between TCP and UDP, and which suits industrial telemetry?
TCP is connection-oriented: it performs a three-way handshake, numbers every byte, retransmits lost segments, reorders out-of-order data, and applies flow control via the receive window plus congestion control via algorithms like CUBIC. UDP is connectionless and adds only ports and an optional checksum on top of IP, so it has an 8-byte header versus TCP’s 20-byte minimum and no retransmission or ordering guarantees. TCP suits configuration transfer, file uploads, and MQTT-style broker traffic where a lost byte is unacceptable. UDP suits high-rate sensor telemetry and real-time control loops where a stale retransmitted reading is worse than a dropped one, which is why protocols like EtherNet/IP implicit messaging carry cyclic I/O over UDP.
Q: What is a PLC, and how does its scan cycle work?
A Programmable Logic Controller is a ruggedised industrial computer that executes control logic deterministically against field I/O. Its scan cycle has four repeating phases: read all physical inputs into an input image table, execute the user program (ladder, structured text, or function block) against that frozen image, write the resulting output image to the physical outputs, and then run housekeeping such as diagnostics and communications. Because the program works on a snapshot rather than live inputs, results are repeatable and free of mid-scan glitches. Typical scan times are a few milliseconds, and your logic must complete within the configured watchdog time or the PLC faults to a safe state.
Q: What is a VFD, and how does it control the speed of an induction motor?
A Variable Frequency Drive rectifies incoming AC to a DC bus, smooths it with a capacitor bank, and then inverts it back to AC at a chosen frequency using IGBTs switched by pulse-width modulation. Induction motor synchronous speed is Ns = 120f/P, so changing the output frequency directly changes speed. To keep the magnetic flux constant and avoid saturating the core, the drive holds the voltage-to-frequency ratio roughly constant below base speed, the classic V/f control law; above base speed it enters field weakening at constant voltage. Beyond speed control, VFDs cut inrush current by ramping up smoothly and save significant energy on pump and fan loads, where power varies roughly with the cube of speed.
Q: What is edge computing, and why does industrial automation use it instead of sending everything to the cloud?
Edge computing runs processing on gateways or controllers physically near the machines rather than in a remote data centre. Industrial plants use it because control loops need round-trip latency in the millisecond range, which a WAN link to a cloud region cannot guarantee, and because a plant must keep running when the internet link drops. It also cuts bandwidth cost dramatically: a vibration sensor sampling at kilohertz can be reduced at the edge to a few features per second before upload. The usual architecture is hybrid, with the edge handling real-time control, filtering, and anomaly detection, and the cloud handling long-term historian storage, fleet-wide analytics, and model training that is then pushed back down to the edge.
Frequently asked questions about ABB interviews
Section titled “Frequently asked questions about ABB interviews”What is the ABB interview process for freshers?
ABB’s process typically runs 4-5 rounds: 1. Online Test (about 60 minutes) - verbal, analytical/reasoning, attention-to-detail, and a technical/branch section. 2. Group Discussion (only when the applicant pool is large) - 5 minutes to prepare, then a moderated discussion on a current-affairs or industry topic. 3. Technical Interview (about 60 minutes) - a senior ABB engineer goes through your resume almost line by line, plus core CS/EE/automation fundamentals; candidates are sometimes asked to name 2-3 preferred domains for deep discussion. 4. HR Interview (20-30 minutes) - culture fit, and on some drives a case-study presented on chart paper without slides. 5. A closing psychometric test and salary discussion.
What questions are asked in ABB interviews?
Technical rounds lean heavily on your resume and projects - expect the interviewer to pick apart almost every line, so be ready to explain design choices and outcomes in detail. Beyond that, common topics are C++/Java fundamentals, OOP, DBMS, operating systems, computer networking, and core electrical/automation/power-electronics concepts (ABB is a power and automation technology company), along with domain questions like edge vs. cloud, IoT, and robotics/PLC basics depending on the business unit.
How many rounds are there in the ABB interview?
Most ABB campus drives run an Online Test, an optional Group Discussion (added when there are many applicants), a Technical Interview, an HR Interview, and sometimes a closing psychometric test - typically 4-5 stages in total. Not every drive includes the GD or psychometric stage; it depends on applicant volume and the specific business unit hiring.
How should I prepare for ABB interviews?
Know every project on your resume cold, since ABB interviewers tend to interrogate it line by line. Brush up OOP, DBMS, OS, and networking basics, and if you’re from an electrical/instrumentation background, revisit core power-electronics, automation, and control concepts. For the HR round, be ready to think on your feet - some ABB drives close with an unscripted case-study pitch presented on chart paper rather than slides.
Does ABB hire for both electrical/automation and software roles?
Yes. ABB is a power and automation technology company (electrification, robotics and motion, process automation), so campus hiring spans core electrical/automation engineering roles alongside software roles supporting those product lines. The online test branch-splits its technical section accordingly, and the technical interview probes whichever domain(s) you list as your preference.
What is the ABB chart-paper case-study round?
On some drives, the HR or final round includes an unscripted case study or business-idea pitch that you present to the panel using only a chart paper and markers - no slides. It’s designed to test structured thinking and communication under pressure rather than design skill, so focus on a clear, logical structure (problem, approach, impact) rather than making it visually polished.