| With the introduction of the Type I meter, the TRW prepayment gave way to a new model, the Type IP. The two parts
of this system were retained, but the Type IP had a standard kilowatthour register instead of the specially-marked register of the
prepayment TRW. As with the prepayment TRW, the IP had a contact device that tripped the coil in the prepayment device. The prepayment
devices used with the IP were also redesigned. The Form 3 device (center) could be adapted to take either dimes or quarters, while
the Form 4 device (right) accepted only quarters. |