• Provides Relay Contact Closures at Preset Thermocouple Input
• Cold Junction Compensated
• Fail-Safe, Latching, and Adjustable Deadband Available
• Red and Green LED Alarm Status Indicators
• 5 mV Minimum Input Span
• Unlimited Choice of Input Ranges ( Within specified range limits)
• Upscale Burnout Protection (Downscale Available)
• Choice of Power Options
• 10 Year Warranty

The MM1220 monitors any thermocouple input signal and provides two sets of spdt, 5 A alarm relays with two independently adjustable setpoints. Each setpoint has a set of red/green LEDs to indicate alarm status. When the input is between the setpoints, the relays are normally deenergized. When the signal exceeds a particular setpoint, the relay becomes energized. To provide a fail-safe operation (loss of power resulting in alarm state), select Option R. The module can be supplied as a HI/HI, HI/LO, or LO/LO alarm (HI/LO supplied if not specified).

Standard deadband on both alarms is fixed at 0.5% of span. (Option A provides adjustable deadband of 0.5% to 100% of span.) Option D, latching alarms, has no deadband control. Once the limit has been reached, the alarm latches and power to the module must be momentarily interrupted to reset the alarm.

Cold junction compensation is provided by a solid state temperature sensor embedded in the thermocouple terminal strip.

All Wilkerson products are designed with RFI filters and lightning protection to reduce susceptibility to electrical noise and damage by lightning.

Upscale burnout protection is provided as standard. In the event the thermocouple opens, the module behaves as though the input goes offscale high. Option B provides downscale burnout protection (module behaves as though the input goes low).

TYPICAL APPLICATIONS
Heater/cooler control, HI/LO temperature alarm.

INPUT RANGE select any type thermocouple (min span 5 mV) SETPOINT 0 to 100% of span DEADBAND Standard fixed 0.5% of span (Option A) 0.5% to 100% of span (Option D) Latching, Interrupt power to reset RELAY CONTACTS (spdt) Resistive Load 5 A max,    150 W max, 220 VAC max, 30 VDC max Inductive Load (power factor >0.4)    2.5 A max, 75 W max, 220 VAC max, 30 VDC max TRANSISTOR OUTPUT (Option V) relay driver (12 V coil, >220 ohms) or open-collector outputs sink 100 mA, 30 V supply max

ACCURACY ±0.1% of span COMMON MODE REJECTION 120 dB, DC to 60 Hz OPERATING TEMPERATURE 14°F to 140°F/–10°C to 60°C TEMPERATURE STABILITY ±(0.02% of span + 1.3 μV)/°C max POWER 115 VAC ±10%, 50/60 Hz (2.5 W max) 230 VAC ±10%, 50/60 Hz (2.5 W max) (DC Power Option) 24 VDC (limits 21-32 VDC) 12 VDC (limits 10-16 VDC) Isolation, DC power supply to input common: 10 megohms

T/C Input + T/C Input + PIN 1 PIN 2 PIN 3 PIN 4 PIN 5 PIN 6 PIN 7 PIN 8 PIN 9 PIN 10 PIN 11

T/C Terminal+ T/C Terminal - Power AC L1 or DC + No Connection Power AC L2 or DC - No Connection No Connection Relay Set 1 NO Relay Set 1 C Relay Set 1 NC Relay Set 2 NO Relay Set 2 C Relay Set 2 NC