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Last Post 09/04/2009 8:06 AM by  Tony Hodges
Relay application question
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Tony Hodges
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09/04/2009 8:05 AM
    This concerns your CR5395 current sensing relay system (the "device"), applied to a charger system for an electric vehicle. The attached diagram reflects my current configuration, "as built" (I contributed the diagram to Wikibooks).

    I will shortly be installing 8 small isolated chargers to float charge my 96 volt (16 x 6V) pack in order to reduce cooling fan wear and noise on the bulk charger. The in-vehicle bulk charger (K&W)is powered through a vehicle mounted relay ("Ry CP")whose purpose is to isolate the controller pre-charge circuit, with one of the contacts providing power to the bulk charger after the isolation occurs. This is required by this system as the normal leakage currents through the motor would otherwise trip the GFCI in the K&W charger.

    I wish to disconnect the K&E charger when the bulk charging current drops to about 1 amp DC. I intend to do this by interrupting the 110VAC to the isolation relay coil, so the current controlling requirements by the sensing device are small. I also want to power your device from 110VAC and prefer that it be completely disconnected (unpowered) when inactive. Bulk charger start-up time appears to be less than a second (the charger incorporates "soft start" to limit AC and DC inrush currents), but longer delays are OK.

    It appears that by using the power applied to the bulk charger to power the CR5395 device and using the relay contacts to break the current to the isolation relay I can satisfy my needs, providing:

    1.) Some contact on the device relay is closed when no power is applied to the CR5395 and closure continues for some limited time while the power is applied to the charger and the device and the DC charging current ramps up.

    2.) The CR5395 relay remains closed during bulk charge and only opens when the DC current is below the threshold set (1 to 2 Amperes).

    In the attached diagram your device would interrupt the power provided through fuse "F-CR" and be powered via the "C"(3)contact relay "CP", which provides AC power to the charger.

    As an alternative, I can apply device power from the "F-CR", the device being powered as long as the vehicle is plugged in to a powered AC circuit, which will be most of the time.

    Can you recommend the correct device from your series?



    Tony Hodges
    CRM Staff
    Basic Member
    Basic Member
    Posts:154


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    09/04/2009 8:06 AM
    The 5395 has a SPDT forms class C output with normally open and normally closed connections. In the unpowered or untripped state, the NC will be connected to the C. A time delay setting can accomplish the start up issues, however, this same delay will be in effect on tripping. The output relay will delay the setting after the trip point is met.

    You will need the EL unit, which is energize when the current goes below the setpoint. I also recommend the 1- 10 amp trip range unit. The relay can handle physically over 100 Amps continuous through the CT sensor, even though the range is 1 to 10. The delay of 1 second would put you in the middle of the “A” delay timing. So your part number would be:

    CR5395-EL-ACV-110-A-CD-ELR-I
    This is the part number with the ring included with the relay.

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