AIS-138 Explained: What EV Charger Engineers Need to Know

Scope of AIS-138

AIS-138 covers electric vehicle conductive charging systems in India. It is closely aligned with IEC 61851-1 but includes India-specific requirements for grid conditions and climate.

Key Electrical Requirements

Supply Voltage Tolerance

India's grid fluctuates significantly. AIS-138 requires operation across:

Single phase: 180V AC – 260V AC

Three phase: 300V AC – 460V AC

Dielectric Strength (Hipot)

For a 230V AC charger, the standard specifies 2,000V AC for 1 minute between live parts and protective earth. DC chargers require 4,000V AC isolation between input and output.

Safety Mandates

IP Rating: IP55 minimum for outdoor installations; IP67 for portable chargers.

Ground Fault: RCD must detect and interrupt faults < 30 mA within 40 ms.

Connectors: Type 2 for 4W AC; Bharat AC001/DC001 for public infra.

Communication Protocols

For DC fast chargers (AIS-138 Part 2):

CCS2: ISO 15118 + IEC 61851-23 (PLC communication).

Control Pilot (CP): 1 kHz PWM signal communicating max available current.

Certification Process

Pre-compliance: Internal safety and functional tests.

Submission: To NABL labs like ARAI (Pune) or ICAT (Manesar).

BIS License: Submit test reports for IS 17017 license.

Timeline: Expect 6–9 months from prototype freeze to full BIS certification.