[GeoffT]

I'm planning to change my Rolec 32A charger from tethered to untethered. I have a Viridian E32F32 EPC to replace the Rolec unit. Does anyone please have a wiring diagram specifically for this swap to illustrate what goes where to save me having to partly reverse engineer the unit?

MTIA.

 

[HandyAndy]

I've only done a 1-for-1 replacement of untethered Rolec ECU to untethered Viridian ECU, and I used the Viridian manual. Main difference was the polarity of the LED uni is reversed on V, so I binned that and covered the hole with clear window. Viridian has its own built-in LED, so not an issue. But I think you're going to have to look at their diagram, and see just where that cable resistor goes, the one that identifies if it's 13A, 20A, or 32A cable being used. There's also a J1772 spec out on the web somewhere; old, but I believe still relevant. My download was called "finalsaej1772.doc". PM me if you can't find it, & i can email you a copy.

 

[barneyd]

There’s more to this than a simple swap. The untethered spec requires the unit to know the current rating of the cable so that a 16A cable is adequately protected and isn’t just fed from the 32A RCBO.

You need two contactors, one fed from a 32A breaker and the other from a 16A breaker. The controller then closes the appropriate contactor based on the rating of the cable. The cable rating is picked up by measuring a resistor that is present in the plug, so you need to wire that from the socket to the controller.

If you are the only person who will ever use the chargepoint, you could just connect your existing contactor to the 32A coil feed but it wouldn’t work with anyone else’s 16A cable.

 

[freddym]

There’s more to this than a simple swap. The untethered spec requires the unit to know the current rating of the cable so that a 16A cable is adequately protected and isn’t just fed from the 32A RCBO.

You need two contactors, one fed from a 32A breaker and the other from a 16A breaker. The controller then closes the appropriate contactor based on the rating of the cable. The cable rating is picked up by measuring a resistor that is present in the plug, so you need to wire that from the socket to the controller.

If you are the only person who will ever use the chargepoint, you could just connect your existing contactor to the 32A coil feed but it wouldn’t work with anyone else’s 16A cable.

Eh????

 

[GeoffT]

There’s more to this than a simple swap. The untethered spec requires the unit to know the current rating of the cable so that a 16A cable is adequately protected and isn’t just fed from the 32A RCBO.

You need two contactors, one fed from a 32A breaker and the other from a 16A breaker. The controller then closes the appropriate contactor based on the rating of the cable. The cable rating is picked up by measuring a resistor that is present in the plug, so you need to wire that from the socket to the controller.

If you are the only person who will ever use the chargepoint, you could just connect your existing contactor to the 32A coil feed but it wouldn’t work with anyone else’s 16A cable.

Both my cables are 32A, one a fully-wired 3-phase cable, so I'm pretty relaxed about this point. I wondered why the EPC wiring diagram does show three options for wiring - 16A, 32A and 63A - each wired through it's own similarly rated circuit breaker. And the EPC maximum current limiting resistor is set for 32A.

 

[freddym]

The MCB is there to protect the design load of the EVSE or its supply cable depending on where it is located. It's not there to protect downstream separate equipment such as the car itself or the plugged in cable. That's provided for by the cable control resistor.

 

[barneyd]

The MCB is there to protect the design load of the EVSE or its supply cable depending on where it is located. It's not there to protect downstream separate equipment such as the car itself or the plugged in cable. That's provided for by the cable control resistor.

How is a 16A cable protected then? The resistor tells the controller which protection to invoke, it doesn’t itself protect the cable.

 

[barneyd]

Both my cables are 32A, one a fully-wired 3-phase cable, so I'm pretty relaxed about this point. I wondered why the EPC wiring diagram does show three options for wiring - 16A, 32A and 63A - each wired through it's own similarly rated circuit breaker. And the EPC maximum current limiting resistor is set for 32A.

That’s it. You wire two (or three) contactors in parallel, each with the relevant protection. The controller reads the resistor and works out the rating of the cable and then closes the contractor with the appropriate overload device upstream of it.

 

[freddym]

How is a 16A cable protected then? The resistor tells the controller which protection to invoke, it doesn’t itself protect the cable.

Its a control system NOT a protection system qed.

The control system, selects EITHER of the lowest amperage that the CAR or the CABLE request. There is no bespoke protection tailored to the CAR or the CABLE.

Recall that FIXED protection systems protect FIXED wiring. A plug in cable is NOT part of the FIXED wiring.

 

[freddym]

That’s it. You wire two (or three) contactors in parallel, each with the relevant protection. The controller reads the resistor and works out the rating of the cable and then closes the contractor with the appropriate overload device upstream of it.

NO NO NO NO NO, deary me!

 

[freddym]

NO NO NO NO NO, deary me!

Similar to a ring circuit protected by a 32A MCB, no-one changes the value of the MCB depending on what PORTABLE equipment is plugged in.

 

[barneyd]

Similar to a ring circuit protected by a 32A MCB, no-one changes the value of the MCB depending on what PORTABLE equipment is plugged in.

That's right, because there is lower value protection in the form of a fuse in the plug or FCU to protect the portable equipment and its cable.

 

[barneyd]

NO NO NO NO NO, deary me!

Will you tell the designers of the equipment or do we think they don't know what they are talking about?

 

[barneyd]

Its a control system NOT a protection system qed.

The control system, selects EITHER of the lowest amperage that the CAR or the CABLE request. There is no bespoke protection tailored to the CAR or the CABLE.

Recall that FIXED protection systems protect FIXED wiring. A plug in cable is NOT part of the FIXED wiring.

How does that protect the cable against a short circuit at the car end?
The controller tells the car to draw no more than 16A through the cable and the car doesn't but the fault does. The controller just signals to the car and the contactor, it can't protect against the fault.

 

[freddym]

I suspect a short circuit will trip a 32A MCB pretty dam% quick.

If its overload you are thinking about, the control system will do its job.

 

[barneyd]

the control system will do its job.

How would the control system would know there was an overload? It doesn’t measure current.

 

[barneyd]

I suspect a short circuit will trip a 32A MCB pretty dam% quick.

I‘m sure I remember the regulations quoting the required disconnection time in seconds. (Actually fractions of a second for socket outlets)