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EV Charging CP and PP Explained: Control Pilot and Proximity Pilot

CP means Control Pilot. PP means Proximity Pilot. They help a Type 2 EV charging system recognise the connection, establish charging readiness and work within the permitted current. They are signalling contacts, separate from the conductors carrying power to the vehicle.

This guide explains the basic Type 2 AC charging interface. It is an explanation of how the system works, not a wiring or live-testing procedure.

CP and PP at a glance

The two pilot functions in a Type 2 charging connection
Signal Main job
CP — Control Pilot Communicates connection and readiness states, and the current the charge point makes available.
PP — Proximity Pilot Provides plug-presence information and, for a detachable Type 2 cable, identifies its current capability through resistor coding.

Neither signal carries the vehicle’s charging power. PE means Protective Earth; it has a different role from the neutral conductor. Pilot signalling uses a reference to PE, but successful signalling alone does not prove that an installation has passed its electrical safety tests.

How Control Pilot works

The charge point, also called EVSE, generates the CP signal. Basic signalling uses a nominal 1kHz waveform derived from a ±12V source. The vehicle changes the electrical loading of that signal to indicate its connection and readiness state. The charge point’s PWM duty cycle — the proportion of each cycle spent high — communicates the available current.

These are two different pieces of information: the detected voltage level describes the vehicle state; the duty cycle describes the current allowance. Texas Instruments explains both functions in its EVSE controller design guide, sections 2.2.1 and 2.2.3.

The main CP connection states

Simplified nominal CP states
State Positive level Meaning
A +12V No vehicle detected.
B +9V Vehicle connected, not ready for charging.
C +6V Vehicle ready for charging without a ventilation requirement.
D +3V Vehicle requests charging with ventilation; the charge point must support that requirement.

These are nominal positive signal levels, not a set of expected average multimeter readings. Other states and fault conditions exist. State C indicates readiness; authorisation, locking and the charge point’s other checks still apply before power is supplied. See Beckhoff’s IEC 61851 communication-state documentation.

How Proximity Pilot works

A detachable Type 2 cable needs to identify its current capability because users can connect different cables to the same charge point. The PP function uses a coded resistance associated with the plug/cable assembly. The charging equipment uses that information when establishing the permitted charging current.

That coding describes the assembly’s capability; it is not a measurement of the current flowing and it does not increase the cable’s physical rating. Tethered arrangements differ because the charge point already knows the rating of its permanently attached cable.

The Type 2 implementation should not be confused with Type 1 latch-switch arrangements. HDT’s explanation of CP and proximity functions describes this distinction.

What happens when you connect a vehicle?

  1. The charging system detects the connection and establishes the relevant cable capability.
  2. The CP state indicates that the vehicle is present.
  3. The charge point advertises the current available for charging.
  4. The vehicle indicates readiness. Once the required permissions and checks are satisfied, the charge point can close its power contactor.
  5. The vehicle’s charging controls keep its draw within the permitted limit. The limit may change during the session.

This is an overview, not an exhaustive commissioning sequence. The vehicle can draw less than the advertised allowance because of its own charging limits, battery state or other conditions.

Why a 32A cable does not guarantee 32A charging

A cable’s rating is a ceiling, not a demand. The usable current is constrained by the supply, charge point, cable and vehicle. A charge point with load management can advertise a lower allowance even when a higher-rated cable is connected.

For ordinary PWM-based AC signalling, the advertised current limit applies per phase. Available current and the number of phases both matter when interpreting a kW figure. A three-phase headline power rating is not the power available from one single-phase outlet.

Our adjustable 32A portable Type 2 EV charger is an example of vehicle-charging equipment with selectable current settings. Read using an adjustable portable EV charger at home and away for the product’s applications and supply checks.

What this means for Type 2 power adapters

An auxiliary power adapter is a different application from charging an EV. A successful connection handshake does not, on its own, demonstrate that a general-purpose load will respond to a changing CP current allowance.

PP coding is not a fuse, and CP signalling is not an automatic current regulator for an ordinary appliance. Compatibility depends on the complete adapter design, connected equipment, protection and charge-point behaviour. Do not assume that a passive code or an energised output guarantees load-management compatibility.

Read our EV Charging Adapter Applications guide and the exact product instructions. Confirm the operator’s permission for auxiliary use. Pilot signalling is not a substitute for protective devices or a safety assessment.

Adapters for vehicle charging

The Type 2 to Type 1 in-line EV adapter is a vehicle-charging product. Check its specified vehicle and charge-point compatibility. Its application differs from the auxiliary power converters below.

Converters for auxiliary power

Browse the full Type 2 socket converter range for other output formats. Choose by the required connection and intended application, then check the individual product instructions.

Testing and fault-finding

Our EVSE and tethered-cable test adapter provides an interface for appropriate electrical test equipment. Testing requires a competent person and the manufacturer’s procedure; a successful functional check is not a complete installation test.

For more about the distinction between pilot communication, protective-earth checks and residual-current monitoring, see the Bender CC613 manual, sections 4.3.4–4.3.8.

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