Ko te pūnaha rokiroki pūngao (ESS), e ai ki te ingoa, he pūnaha e whakamahia ana hei penapena pūngao, e pā ana ki te hurihanga o te pūngao hiko i roto i te pūnaha hiko hei momo taputapu ka taea te penapena i te pūngao kia taea ai te huri anō ki te pūngao hiko ina hiahiatia. Ko te pūnaha hiko kore-mutu (UPS) he pūtake hiko whakauru e whakarato ana i te hiko ohorere ki te kawenga ina pakaru te pūnaha hiko matua o te taputapu hiko, e whakamahia ana hei tiaki i ngā taputapu e hiahiatia ana he nui mō te pumau o te pūnaha hiko. Mēnā ka pakaru, ka whakaratohia he hiko AC tārua mō ngā taputapu kawenga hiko me te kore e motuhia kia mau tonu ai te mahi noa o ngā taputapu hiko. Kei roto i ēnei pakaru ko te motuhanga hiko, te ngaohiko iti, te pokanoa, te ngaru rānei.

He rerekē te ESS whānui i te pūnaha UPS.

Tuatahi, ko te whakamahinga o te pūnaha UPS he mahere ohorere e puta ana ina pakaru te pūtake hiko matua. Haunga te ohorere, ka whakamahia te pūtake hiko i roto i te ESS mō te kawenga tihi i roto i te maha o ngā wā, ā, ka whakamahia mō te "tapahi tihi me te whakakī awaawa" me ētahi atu momo hiko, pērā i te hiko karihi, te hiko hau, te hiko rā, me ētahi atu. Ka taea te whakawhiti hiko hei whakaiti i ngā utu, hei āwhina rānei i aua pūtake hiko motumotu kia kaweake tonutia. Tuarua, ko te UPS, hei pūnaha ohorere, he tikanga hei pupuri i te pumau o ētahi taputapu matua, kia whai wā ai rātou ki te kati noa, kia tahuri rānei te hiko ohorere, nō reira kāore i te roa te roa, he tekau meneti noa iho, he torutoru meneti rānei, kātahi ka tahuri te hiko ohorere, ka ahu mai pea te hiko ohorere i te pūnaha ESS, i ētahi atu kaihanga hiko tūmatanui rānei. Hei whakamutunga, he taputapu rokiroki hiko anō hoki kei te pūnaha UPS, ka whakamahia e ētahi pūnaha UPS te pūnaha wira rere hei penapena hiko, ka whakamahia e ētahi pūnaha UPS ngā pūnaha pākahiko hei penapena hiko, engari i te wā rangimārie hoki hei utu i te pūnaha rokiroki hiko, ina raru te pūnaha hiko matua, ka tīmata te UPS ki te whakarato i te pūtake hiko korekore.