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Dry Contacts
The PMH3XLM includes a set of Dry Contacts available at a terminal block at the right-front of the inside panel. This
feature provides two sets of normally open (NO) and normally closed (NC) contacts which can be used for remote
monitoring of the PMH3XLM’s operating status by changing state when there is an alarm condition. Examples of
remote monitoring equipment include a computer interface board, emergency management system, or APC’s
Environmental Monitoring Unit Option (see Environmental Monitoring Unit Option). The relay contact pin
arrangement is outlined in Table 2. (Note: The jumpered connections of Pins 7, 8, & 9 do not represent a third set of
contacts).
For applications using Dry Contacts, please note the following information:
• The Dry Contacts are designed for low voltage or control signals only. The maximum switching current is 1
amp. The maximum switching voltage is 24 volts, DC or AC.
• Higher energy applications may require additional relay implementation outside the PMH3XLM. Damage to
the PMH3XLM unit’s relay caused by implementation with energy levels in excess of those discussed in this
manual will not be covered by warranty.
Note that the Dry Contacts will allow the PMH3XLM unit to communicate with one (1) external device.
NOTE: Pin pairs 4 & 7, 5 & 8, and 6 & 9, are connected via jumper
internally. The combined current of each pin pair may not exceed 1 Ampere.
Environmental Monitoring Unit Option
APC offers a Environmental Monitoring Unit Option, which allows the user to monitor the alarm status of the
connected SPD. The product is available as a 120-volt external power supply (AP9312PM) or as a 100-240 volt
universal input external power supply (AP9312PMI).
The AP9312PM is connected to the SPD using Dry Contacts. When an alarm is triggered, the Dry Contact closes and
the Environmental Monitoring Unit Option sends up to four e-mail messages to preprogrammed addresses, notifying
the address that the SPD is in an alarm condition. The e-mail messages can be sent to computers, pagers, cell phones,
or Palm
®
Computers anywhere in the world over the internet.
The AP9312PM has its own internet protocol (IP) address and is usually connected to a 10Base/T communications
network. It then uses its internal browser software to host a web page on the internet. Facility managers can monitor
the status of the Environmental Monitoring Unit using their computer and internet browser, such as Microsoft
®
Internet Explorer
®
. An qualified/licensed electrician is required for installation of the Environmental Monitoring
Unit Option to the Dry Contacts of the SPD.
Page 7
Table 2: Relay Contact Pin Arrangement
Pin Contact Type
Relay Contact
Set 1
Form "C"
1 Normally Closed (1)
2 Common (1)
3 Normally Open (1)
Relay Contact
Set 2
Form "C"
4,7 Normally Closed (2)
5,8 Common (2)
6,9 Normally Open (2)